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JOURNAL 


THE    CHEMICAL   SOCIETY. 


/    '       I 


TRANSACTIONS. 


HoKACK  T.    B»owH,  LL.D.,  F.R.S. 
J.  I>BWAR,   L.L.I>.,  F.R.S. 
Wtndham   R-    Ditnstan,  M.A.,  F.R.S. 
C.  E-   Grovks,  F.B-S. 
A.  Vmtifoii  HiLKCOintT,  M.A.,  F.R.S. 
C.  T.  Mexcjock,  M.A.,  F.E.S. 


%vtmi!i\u  sA  ^nbluHtum; 


R.  Meldola,  F.R.S. 

H.  FORSTER  MORLET,  M.A.,  D.So. 

A.  Scott,  D.Sc,  F.RS. 

T.  E.  Thorpe,  LL.D.,  F.R.S. 

W.  A.  TiLDEN,  D.Sc.  F.R.S. 


C.  K  Groves,  F.R.S. 

W.  P.  Wynne,  D.Sc,  F.B.S. 


A.  J.  Grssnaway. 


1899.    Vol.  LXXV. 


LONDON: 
GTJRNBY    A  JACKS0N,3l,   PATERNOSTER  ROW. 

1899. 


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BiGHAUP  GlJ^T  AND  SOMS,  LiMirRli 
LOHDOR   AND  BUNOAV. 


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JOURNAL 

OF 

THE    CHEMICAL  SOCIETY. 


TRANSACTIONS. 


tmtmaittt  oi  ^nblitistvmi 


Ho&ACS  T.  BaowN,  LL.D.,  P.R.S. 
J.  TfmwASL,  I.L..I>.,  F.R.S. 
yrmmiKAM.  'EL   DTTKBTAir,  M.A.,  F.ItS. 
C.  E.  Gkovbs,  F.B.S. 
A.  Ymkjsov  Harcjoitbt,  M.A.,  F.R.S. 
C.  T.  HLbtooox,  M.A.,  F.K.8. 


R.  Mbldola,  F.R.S. 

H.  FOBBTBR  MOSLXY,  M.A.,  D.Sc. 

A.  Scott,  D.Sc,  F.B.S. 

T.  E.  Thobpb,  LL.D.,  F.E.S. 

W.  A.  TiLDBN,  D.Sc.-,  F.R.S. 


C.  E.  Geotes,  F.R.S. 

W.  P.  WTimB,  D.Sc,  F.R.8. 


A.  J.  Gbbenawat. 


Vol.  LXXV.    Parti. 


LONDON: 
aXJRNBY    <k  JACKSON,   1,   PATERNOSTER  ROW. 

1899. 


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UiOHARD  Cult  and  Buns,  Liuitbd, 

LOKDOK  AND  BUMOAT. 


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JOURNAL 


OF 


THE    CHEMICAL  SOCIETY. 


TRANSACTIONS. 


tsrmaaiUt  of  ^ttblitatton ; 


Mo&ACK  T.  Browk,  LL.D.,  P.E.S. 
J.  Okwar,  LLu  D.,  F.R.8. 
TV^-raDHiLic  R.    DiTNSTAir,  H.A.,  F.R.S. 
C.  K.  Grovks,  F.R.S. 
A.  Vkrnon^  Harcoitet,  M.A.,  F.B.S. 
C    T.  Heycock,  M.A.,  F.R.S. 


R.  Meldola,  F,R.S. 

H.  FOBSTSR  MOBLBT,  M.A.|  D.Sc. 

A.  SooTT,  D.So.,  F.B.S. 

T.  E.  Thorpe,  LL.D.,  F.B.S. 

W.  A.  TiLDBN,  D.Sc.,  F.R.S. 


Cbtlors : 

C.  S.  Oroybs,  F.R.S. 

W.  P.  Wynne,  D.Sc,  F.R.S. 


j$»b-ffbitor: 

A.    J.    OSBEHAWAT. 


1899.    Vol.  LXXV.    Part  II. 


LONDON: 
OXTRNEY  k  JACKSON,  1,  PATERNOSTER  ROW. 

1899. 


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JliOHABO  Clay  and  Som,  Lxmitbd 

LOMDON  AND  BONOAT 


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CONTENTS. 

PAPERS  READ  BEFORE  THE  CHEMICAL  SOCIETY. 

PAGE 

I. — ^The  Oxidation  of  Polyhydric  Alcohols  in  Presence  of  Iron. 

By    Hbkrt    J.    HoBSTMAK    Fbkton,    M.A.^  and    Henbt 

Jackson,  B.A.,  B.Sc. 1 

n.— j8-Aldebydopropionic     Acid,    CHO-CHg-CHj-COOH,     and 

/8-Aldehydoisobutyric     Acid,     CHO-CH2-CH(CH3)-COOH. 

By  William  H.  Pebkin,  jun.,  and  Chablbs  H.  G.  SpbaiYklimg  1 1 
IIL — ^Gannabinol.     Part  I.    By  Thomas  Bablow  Wood,  M.A. ; 

Wi.  T.  Newton  Spiybt,  M.A. ;  Thomas  Hill  Eastbbfield, 

M.A.,  Ph.D 20 

lY. — Characterisation  of  Racemic   Compounds.     By  Fbedebio 

Staklet  Kipping  and  William  Jaokson  Pope  ...  36 
Y. — Crystalline  Form  of    Iodoform.      By  William    Jackson 

Pope 46 

YI. — ^j8^-Dimethylglataric  Acid  and  its  Derivatives  ;  Synthesis 

of  cU-  and  Iratw-Caronic  Acids.     By  William  H.  Pebkin, 

Jan.,  and  Joceltn  IF.  Thobpe 48 

'  Yn. — Synthesis  of  a)9)8-Trimethylglutaric  Acid, 

I  C00H-CH(CHg)-C(CH,)2-CH,-C00H. 

\  By  William  H.  Pebkin,  jun.,  and  Jocelyn  F.  Thobpe        .       61 

YIII. — Occurrence  of  Orthohydroxyacetophenone  in  the  Volatile 
r  Oil  of  CMane  glabra.     By  Wyndham  R.  Dunstan,  F.RS., 

I I  and  Thomas  Andebson  Hbnby,  Salters'  Research  Fellow 

1'  in  the  Laboratories  of  the  Imperial  Institute      ...       66 

!         IX. — Occurrence  of  Hyoscyamine  in  the  Hyo9cyamu$  mulietu 
^i  of  India.     By  Wyndham  R.  Dunstan,  F.R.S.,  and  Habold 

I  Bbown,   Assistant  Chemist   in   the  Laboratories   of    the 

',  Imperial  Institute      .  72 

.  I  X. — Preparation  of  Hyponitrite  from  Nitrite,  through  Hydroxy- 

amidosulphonate.    By  Edwabd  Divebs,  M.D.,  D.Sc.,  F.RS., 
and  Tamemasa  Haga,  D.Sc.,  F.C.S.     .        .        .        .        .77 

XL — ^Absorption  of  Nitric  Oxide  in  Gas  Analysis.    By  Edwabd 

,^  DiYEBS,  M.D.,  D.Sc.,  F.RS 82 

'I  XIL — Interaction  of  Nitric  Oxide  with  Silver  Nitrate.      By 

Edwabd  Divebs,  M.D.,  D.Sc.,  F.RS 83 

I  A  2 


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IV  COl^TENTS. 

PAOB 
XIII. — ^Preparation  of   Pure  Alkali    Nitrites.      By  Edward 

DivBES,  M.D.,  D.Sc.,  F.R.S 85 

XrV". — Reduction  of  an  Alkali  Nitrite  by  an  Alkali  Metal.    By 

Edward  Divers,  M.D.,  D.Sc,  F.R.S 87 

XV, — Hyponitrites ;  their  Properties,  and  their  Preparation 
by  Sodium  or  Potassium.  By  Edward  Divers,  M.D., 
D.Sc.,  F.R.S. 95 

XVI. — ^Derivatives  of  Camphoric  Acid.  Part  III.  By  Fred- 
eric Stanley  Kipping,  Ph.D.,  D.Sc.,  F.R.S.       .        .        .125 

XVII. — a-Ketotetrahydronaphthalene.     By  Frederic  Stanley 

Kipping,  Ph.D.,  D.Sc,  F.R.S.,  and  Alfred  Hill        .        .     144 

XVni. — Production  of  Optically  Active  Mono-  and  Di-alkyl- 
/         ozysuccinic    Acids  from  Malic   and  Tartaric  Acids.      By 
Thomas  Purdie,  F.R.S.,  and  William  Pitkeathly,  B.Sc, 
Berry  Scholar  in  Science 153 

XIX. — ^Determination  of  the  Constitution  of  Fatty  Acids. 
Part  I.  By  Arthur  William  Crossley  and  Henry 
Rondel  Le  Sueur 161 

XX. — Some    Halogen    Derivatives  of    Acetone   Dicarboxylio 

Acid.    Part  I.    By  Frederick  W.  Dootson,  M.A.    .        .     169 

XXI. — Action  of  Chlorosulphonic  Acid  on  the  Paraffins  and 
other  Hydrocarbons  as  a  means  of  Purifying  the  Normal 
Paraffins.     By  Sydney  Young,  D.Sc,  F.R.S.       .        .        .172 

XXII. — Oxidation  of  Sulphocamphylic  Acid.  By  W.  H.  Perkin, 

jun. 175 

XXIII. — ^Researches    on  Moorland  Waters.     I.  Acidity.     By 

William  Ackroyd,  F.I.C. 196 

XXIY.— The  Nutrition  of  Yeast.     Part  I.     By  Arthur  L. 

Stern,  D.Sc 201 

XXV. — An  Isomeride  of  Amarine.   By  H.  Lloyd  Snapb,  D.Sc, 

Ph.D.,  and  Arthur  Brooke,  Ph.D 208 

XXYI. — Studies  of  the  Terpenes  and  Allied  Compounds. 
Nitrocamphor  and  its  Derivatives.  lY.  Nitrocamphor  as 
an  Example  of  Dynamic  Isomerism.  By  T.  Martin 
LowRY,  B.Sc 211 

XXYII. — ^The  Action  of  Ammonia  on  Ethereal  Salts  of  Organic 

Acids.    By  Siegfried  Ruhemann 245 

XXYin. — The  Changes  of  Yolume  due  to  Dilution  of  Aqueous 

Solutions.    By  Edward  Bruce  Herschbl  Wade,  M.A.      .     254 

XXIX — Methanetrisulphonic    Acid.      By     Ernest     Harold 

Bagnall,  B.Sc 278 

XXX. — Maltodextrin  :  its  Oxidation-Products  and  Constitution. 

ByHoRACET.BROWN,LL.D.,F.R.S.,and  Jambs  Hills  Millar     286 


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CONTENTS.  V 

PAOX 

XXXL — Attempts  to  Prepare  Pure  Starch  Derivatives  through 
their  Nitrates.  By  Hobaob  T.  Brown,  LL.D.,  E.II.S.,  and 
Jaus  Htllb  Millab 308 

XXXn. — The  Stable  Dextrin  of  Starch  Transformations,  and 
its  Relation  to  the  Maltodeztrins  and  Soluble  Starch.  By 
HoKACB  T.  Bbown,  LL.D.,  F.B;S.,  and  James  Hills  Millar    315 

XXXm. — Position  Isomerism  and  Optical  Activity;  the 
Methylic  and  Ethylic  Salts  of  Benzoyl-  and  of  Ortho-,  Meta-, 
and  Para-toluylmalic  Acids.  By  Percy  Frankxaih),  Ph.D., 
F.B.S./aiid  Frederick  Malcolm  Wharton,  A.I.C.,  late 
Priestley  Scholar  in  Mason  University  College,  Birmingham.     337 

XXXrV. — Some  Begularities  in  the  Botatory  Power  of  Homo- 
logous Series  of  Optically  Active  Compounds.  By  Percy 
Frankland,  Ph.D.,  F.R.S 347 

XXXV. — ^Detection    and    Determination  of    Sucrose    in    the 

Presence  of  Lactose.     By  Edwin  Dowzard  .        .        .371 

XXXVI. — Note  on  Certain.  Isomeric  Tertiary  Benzylthioureas. 

By  Augustus  Edward  Dixon,  M.D 373 

XXXVIL — On  Lossner's  Benzoylethyloxysulphocarbamic  Acid ; 
and  the  Formation  of  Pseudoureas.  By  Augustus  Edward 
Dixon,  M.D 375 

XXXVin. — Action  of  Metallic  Thiocyanates  on  Certain  Sub- 
stituted Carbamic  and  Ozamic  Chlorides;  and  a  New 
Method  for  the  Production  of  Thiobiurets.  By  Augustus 
E.  Dixon,  M.D 388 

ICTCTCIX. — Formation  of  a-Pyrone  Compounds  and  their  Trans- 
formation into  Pyridine  Derivatives.  By  Siegfried 
HUHSMANN 411 

XL. — Hydrolysis  of   the  y-Cyanides  of  Di-substituted  Aceto- 

acetates.    By  William  Trevor  Lawrence  .        .        .417 

XLI. — Bromomethylfurfuraldehyde.  By  Henry  J.  Hobstman 
Fbnton,  M.A.,  and  Miss  Mildred  Gostling,  B.Sc,  Bathurst 
Student  of  Newnham  College 423 

XLII. — ^A  Reaction  of  some  Phenolic  Colouring  Matters.     By 

Arthur  George  Perkin,  F.R.S.E 433 

XLUI. — ^A  Method  of  Studying  Polymorphism,  and  on  Poly- 
morphism as  the  Cause  of  some  Thermal  Peculiarities  of 
Chloral  Hydrate.    By  William  Jackson  Pope  .     455 

XLIV. — Contribution    to    the    Characterisation   of    Bacemic 

Compounds.     By  A.  Ladenburg 465 

XLT. — Etherifieation  Constants  of  Substituted  Acetic  Acids. 

By  John  J.  Sudborouoh  and  Lorenzo  L.  Llotd  467 


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VI  CONTENTS. 

Pi.as 
XLVI. — ^The  Eotatory  Powers  of  Optically  Active  Methoxy- 
and  Ethozy-propionic  Acids  prepared  from  Active  Lactic 
Acid.  By  Thomas  Pubdie,  F.R.S.,  and  James  C.  Ibvinb,  6.Sc.     483 

XLYII. — Position-Isomerism  and  Optical  Activity.  The  Com- 
parative Rotatory  Powers  of  Methylic  and  Ethylic  Ditoluyl- 
glycerates.  By  Percy  Fbankland,  F.R.S.,  and  Henry 
Abton,  late  Priestley  and  Forster  Scholar  in  Mason  Uni- 
versity College,  Birmingham 493 

XLVIII. — Isomeric  Fencholenic.  Acids.    By  George  Bertram 

CocKBURN,  B.A.,  B.Sc. 501 

XLIX. — Synthesis  of  some  Derivatives  of  )9)8'-Dipyridyl  from 
Citraziaic  Acid.  By  W.  J.  Sell,  M.A.,  F.I.O.,  and 
H.  Jackson,  B.A.,  B.Sc.    .......    507 

L. — ^The  Condensation  of  Oxalic  Acid  and  Resorcinol.     By  John 

Theodore  Hewitt  and  Arthur  Ernest  Pitt      .        .        ,    5J6 

LI. — Synthesis  and  Preparation  of  Terebic  and  Terpenylic  Acids. 

By  W.  Trevor  Lawrence 527 

LII. — Ethyl    Ammoniumsulphite.     By    Edward    Divers    and 

Masataka  Ogawa 533 

LIII. — Ethyl  Ammonium  Selenite  and  the  Non-existence  of 
Amidoselenites  (Selenosamates).  By  Edward  Divers  and 
Seihachi  Hada. .    537 

LIV. — The  Action  of  Certain  Acidic  Oxides  on  Salts  of  Hydroxy- 
acids.  IV.  By  George  Gerald  Henderson,  D.Sc.,  M. A., 
Thomas  Workman  Orr,  and  Robert  J.  Gibson  Whitehead    542 

LY. — Derivatives  of   oa'-Dihromocamphorsnlphonic  Acid.     By 

Arthur  Lapworth 558 

LVI. — Crystalline  Glycollic  Aldehyde.     By  Henry  J.  Horstman 

Fbnton,  M.A.,  and  Henrt  Jackson,  B. A.,  B.Sc.  .        .         .    575 

LVII. — ^Diortho-substituted  Benzoic  Acids.  P^urt  IV.  Form- 
ation of  Salts  from  Diortho-substituted  Benzoic  Acids  and 
different  Organic  Bases.  By  Lorenzo  L.  Llotd  and  John 
J.  SudboeOugh 580 

L  VIIL — A  New  Compound  of  Arsenic  and  Tellurium.     By  E.  C. 

SzARVASY,  Ph.D.,  and  C.  Messinger,  Ph.D.         .        .        .     597 

LIX. — The  Combustion  of   Carbon    Disulphide.     By    Harold 

Baily  Dixon  and  Edward  John  Bussell    ....    600 

LX. — ^The  Action  of  Nitric  Oxide  on  Nitrogen  Peroxide.     By 

Harold  Baily  Dixon  and  James  Dysart  Peterrin     •        .613 

LXI. — ^On  the  Mode  of  Burning  of  Carbon.     By  Harold  Baily 

Dixon 630 


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CONTKNTS.  Vll 

PAOB 

LXn. — A  study  of  the  Absorption  Spectra  of  Isatin,  Car- 
bostyril,  and  their  Alkyl  Derivatiyes  iu  Relation  to  Taat- 
omerism.  By  Walter  Nosl  Habtlet,  F.RS.,  and  James 
J.  DoBBiE,  M.  A.,  D.Sc.  640 

LXnL — ^Preparation  of  Acid  Phenylic  Salts  of  Dibasic  Acids. 

By  Samuel  Barkett  Schbtybb,  D.Sc.,  Ph.D.      .  .661 

LXIV.— Oorydaline.     Part  VI.     By  James  J.  Dobbib,  D.Sc., 

M.A.,  and  Alezakdeb  Laubeb 670 

LXV. — ^The  Relative  Efficiency  and  UsefulDess  of  various 
Forma  of  Still-head  for  Fractional  DistillatioD,  with  a 
Description  of  some  new  Forms  possessing  special  Advan- 
tages.    By  Sydnet  Young,  D.Sc.,  F.KS 679 

LXVI. — The  Salts  of  Dimethylpyrone,  and  the  Quadrivalence 
of  Oxygen.  By  J.  N.  Collie,  Ph.D.,  F.R.S.,  and  Thomas 
Tickle,  Salters'  Company's  Research  Fellow  in  the  Research 
Laboratory  of  the  Pharmaceutical  Society  of  Great  Britain     710 

LXYII. — Chemical  Examination  of  the  Oleo-resin  of  Dacryodeg 

hexandra.    By  Andbew  Mobb,  A.R.C.S 718 

LXYin. — ^Sstimation    of    Boric    Acid    mainly    by    Physical 

Proceases.     By  A.  Wynteb  Blyth 722 

LXIX.— The  Blue  Salt  of  Fehling's  Solution  and  other  Cupro- 
tartrates.      By  Obme  Masson,   M.A.,   D.Sc.,   and  B.   D.  . 
Steels,  B.Sc 725 

LXX. — ^The  Allotropic  Modifications  of  Phosphorus.     By  David 

Lbohabb  Chapman,  B.A. 734 

LXXL — Oxidation  of  Furfuraldehyde  by  Hydrogen  Peroxide. 

By  C.  F.  Cboss,  E.  J.  Bevak,  and  Thv.  Heibbbg  .     747 

LXXIL — Active  and  Inactive  Phenylalkyloxyacetio  Acids.     By 

Alex.  McKenzie,  M.A«,  D.Sc 753 

LXXIIL — Some  Derivatives  of  Dimethyldihydroresorcinol.    By 

Abthub  William  Cbosslby        .        ...  .     771 

LXXIY.— Condensation  of  Ethylic  Salts  of  Acids  of  the 
Acetylene  Series  with  Ketonic  Compounds.  By  Sibqfbibd 
RuHEMABN  and  A«  Y.  Cunnikgton      .....     778 

LXXV. — Action  of  Hydrogen  Peroxide  on  Carbohydrates  in  the 
Presence  of  Ferrous  Salts.  By  Robebt  Selby  Mobbbll, 
M.A.,  Ph.D.,  and  James  Mubbat  Cbofts,  B.A.,  B.Sc. .  786 

LXXYI. — ^The  Action  of  Alkyl  Haloids  on  Hydroxylamine. 
Formation  of  Substituted  Hydroxylamines  and  Oxamines. 
By  Wtnbham  R.  Duustan,  F.R.S.,  and  Ebiobst  Couldino, 
B.Sc 792 

LXXYII. — ^The  Condeusation  of  Ethylic  Acetonedicarboxylate 
and  Constitution  of  Triethyllc  O^cinoltricarboxylate.  By 
David  Smiles  Jebdah 808 


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VIU  CONTENTS. 

PAQl 

LXXVIIL — ^The  Colouring  Matter  of  Cotton  Flowers,  Oouypwm 
herbaceum.  Note  on  Bottlerin.  B7  Abthub  Obobge 
Pbekin,  F.R.S.E 826 

LXXIX. — The  Colouring  Matters  contained  in  Dyer's  Broom 
(Geniita  tinctoria)  and  Heather  (CaUuna  vulgarig).  By 
Abthub  Geobob  Pbrkin,  F.B.S.E.,  and  Fbedbbice  Geobge 
Nbwbubt 830 

LXXX. — Researches  on  the  Alkyl-substituted  Succinic  Acids. 
Part  I.  Methods  of  Preparation.  By  William  A.  Bonb 
and  Chables  H.  G.  Spbakeling 839 

TjXXXL — Some  Derivatives  of  Dibenzyl  Ketone.  By  Fbancis 
E.  Fbanois,  B.Sc.,  Ph.D.,  Lecturer  in  Chemistry,  University 
College,  Bristol 866 

LXXXII. — Action  of  Light  and  of  Oxygen  on  Dibenzyl  Ketone. 

By  Emily  C.  Fobtet,  B.Sc 871 

LXXXIII. — ^The  Vapour  Pressures,  Specific  Volumes  and 
Critical  Constants  of  Hezamethylene.  By  Stdnbt  Youno, 
D.Sc.,  F.R.S.,  and  Emily  C.  Fobtby,  B.Sc.  .        .        .873 

LXXX IV. — ^The  Composition  and  Tensions  of  Dissociation 
of  the  Ammoniacal  Chlorides  of  Cadmium.  By  William 
Bobebt  Lang,  D.Sc,  and  Albbbt  Rigaut  ....    883 

TjXXXV. — The  Aluminium-Mercury  Couple.  Part  I.  Action 
of  Sulphur  Chloride  on  some  Hydrocarbons  in  presence  of 
the  Couple.  By  Julius  Bbbbnd  Cohen  and  Fbedbbick 
William  Skibbow,  The  Yorkshire  College  ....     887 

LXXXVL— The  Aluminium-Mercury  Couple.  Part  II.  The 
Action  of  Bromine  on  Organic  Compounds  in  presence  of 
the  Couple.  By  Julius  Bbbend  Cohen  and  Hbnby  D. 
Dakin,  The  Yorkshire  College 893 

LXXXVII. — Experiments  on  the  Constitution  of  Isocamphor- 
onic  Acid.  By  Willlam  Hbnby  Pbbkin,  jun.,  and  Jocblyn 
Field  Thobpb 897 

LXXXVIIL— The  ow-  and  ^rowt-^-Phenylbutane-oaiOj-teicarb- 
oxylic  Acids, 

COOH-  CHj*  CH(CeH5)-  CH(COOH)-  CH^-  COOH. 
By  Jocblyn  Field  Thobpb  and  Willlam  XJdall         .        .     904 

LXXXIX. — Experiments  on  the  Synthesis  of  Camphoric  Acid. 
Part  II.  By  H.  A.  Audbn,  William  Hbnby  Pebkin,  jun., 
and  J.  L.  Ross 909 

XC. — ^The  Action  of  Ethylene  Dibromide  and  Trimethylene  Di- 
bromide  on  the  Sodium  Compound  of  Ethylic  Cyanacetate. 
By  H.  C.  H.  Cabpentbb  and  William  Hbnby  Pebkin,  jun.     921 

XCI. — Influence  of  Substitution  on  Specific  Rotation  in  the 
Bomylamine  Series.  By  Mabtin  Onslow  Fobsteb,  Ph.D.y 
D..Sc.         .        .        . 953 


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CONTENTS.  IX 

PAGE 

XCn. — Studies   of   the  Acids    of   the   Acetylene    Series.     By 

Siegfried  Buhehann  and  Alfred  V.  Cunnington.      .  954 

XCIII. — A  Contribution  to  the  Chemistry  of  the  Mandelic  Acids. 

By  Alex.  McKenzie,  M.A.,  D.Sc 964 

XCrV. — ^Non-existence  of  the  so-called  Suboxide  of  Phosphorus. 

By  "David  Leonard  Chapman  and  F.  Austin  Lidbdry.  973 

XCV.— The  Chlorine  Derivatives  of  Pyridine.  Part  III.  The 
Interaction  of  Chlorine  and  Pyridine  Hydrochloride.  By 
William  James  Sell,  M.  A.,  F.I.C.,  and  Frederick  William 
DooTsoN,  M.  A.  . 979 

XUVl. — Homocamphoronic  and  Camphononic  Acids.  By 
Arthur  Lapworth  D.Sc.,  and  Edgar  M.  Chapman, 
Burrough's  Scholar  in  the  Research  Laboratory  of  the 
Pharmaceutical  Society  of  Great  Britain 986 

XCVII. — The  Action  of  Hydrogen  Peroxide  on  Secondary  and 
Tertiary  Aliphatic  Amines.  Formation  of  Alkylated 
Hydroxy lamines  and  Oxamines.  By  Wyndham  R.  Dunstan, 
F.R.S.,  and  Ernest  Gouldino,  B.Sc ' .  1004 

XCVm. — ^Amidoamidines    of    the    Naphthalene    Series.     By 

Raphael  Meldola,  F.R.S.,  and  Percy  Phillip  Phillips.   .  1011 

XCIX. — Condensations  of  Anhydracetonebenzil  and  its  Ana- 
logues with  Aldehydes.  By  Francis  R.  Japp,  F.R.S.,  and 
Alexander  Findlay,  M. A.,  B.Sc 1017 

C. — ^Triphenyloxazolone.     By  Francis   R.    Japp,    F.R.S.,  and 

Alexander  Findlay,  M.A.,  B.Sc 1027 

01. — Interaction  of  Phenanthraquinone,  Acetopheuone,  and 
Ammonia.  By  Francis  R.  Japp,  F.R.S.,  and  Andrew  N. 
Meldrum,  B.Sc 1032 

OIL — Furfuran  Derivatives  from   Benzoin   and   Phenols.     By 

Francis  R.  Japp,  F.RS.,  and  Andrew  N.  Meldrum,  B.Sc.  1035 

OIXL — Interaction    of   Benzoin  with  Phenylenediamines.     By 

Francis  R.  Japp,  F.R.S.,  and  Andrew  N.  Meldrum,  B.Sc.  1043 

CIV. — A  Series  of  Substituted  Nitrogen  Chlorides  and  their 
Relation  to  the  Substitution  of  Halogen  in  Anilideu  and 
Anilines.     By  F.  D.  Chattaway  and  K.  J.  P.  Orton  .         .  1046 

CV- — Synthetical  Preparation  of  Glucosides.  By  Huqh  Ryan, 
M.A.,  1851  Exhibition  Scholar  of  the  Queen's  College, 
Galway 1054 

CVI. — ^The  Action  of  Sulphuric  Acid  on  Fenchone.     By  James 

E.  Marsh 1058 

CVII. — On  a  Method  for  Providing  a  Current  of  Gaseous 
Chloroform  mixed  with  Air  in  any  desired  proportion,  and 
on  Methods  for  Estimating  the  Gaseous  Chloroform  in  the 
Mixtures.  By  A.  Vernon  Hahcourt,  M.A.,  F.R.S.,  Lee's 
Reader  in  Chemistry  at  Christ  Church,  Oxford  .         .  1060 


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X  CONTENTS. 

PA6£ 

CVIII. — ^The  Application  of  Powerful  Optically  Active  Acids  to 
the  Resolution  of  Externally  Compensated  Basic  Substances. 
Resolution  of  Tetrahydroquinaldine.  By  William  Jackson 
Pope  and  Stanley  John  Peachey 1066 

CDC. — The  Application  of  Powerful  Optically  Active  Acids  to 
the  Resolution  of  Externally  Compensated  Basic  Substances. 
Resolution  of  Tetrahydroparatoluquinaldine.  By  William 
Jackson  Pope  and  Edmund  Milton  Rich  ....  1093 

ex. — The  Application  of  Powerful  Optically  Active  Acids  to 
the  Resolution  of  Externally  Compensated  Basic  Substances. 
Resolution  of  Racemic  Camphorozime.  By  William 
Jackson  Pope 1105 

CXI. — Homogeneity  of  DextrolsBvo-a-phenethylamine  Dextro- 
camphorsulphonate.  By  William  Jackson  Pope  and 
Alpeed  William  BLabvey 1110 

CXII. — A  Method  for  Discriminating  between  **  Non-racemic  " 
and  "  Racemic  "  Liquids.  By  William  Jackson  Pope  and 
Stanley  John  Peachey 1111 

CXIII. — The   Characterisation  of    "Racemic"   Liquids.      By 

Fbedebic  Stanley  Kipping  and  William  Jackson  Pope    .  1119 

CXIV. — Asymmetric  Optically  Active  Nitrogen  Compounds. 
Deztro-  and  Lffivo-a-benzylphenylallylmethylammonium 
Iodides  and  Bromides.  By  William  Jackson  Pope  and 
Stanley  John  Peachey 1127 

CXY. — Tetrazoline.     By   Siegfeied    Ruhemann    and    H.    E. 

Stapleton,  Scholar  of  St.  John's  College,  Oxford        .         .1131 

CXVI. — Action  of  Hydrolytic  Agents  on  a-Dibromocamphor. 
Constitution  of  Bromocamphorenic  Acid.  By  Abthur 
Lapwoeth 1134 

CXVII. — Camphoroxime.  Part  III.  Behaviour  of  Camphor- 
oxime  towards  Potassium  Hypobromite.  By  Mabtin 
Onslow  FoBSTEB,  Ph.D.,  D.Sc.  1141 

CXYIII. — Influence  of  an  Unsaturated  Linking  on  the  Optical 
Activity  of  Certain  Derivatives  of  Bornylamine.  By  Mabtin 
Onslow  FoBSTEE,  Ph.D.,  D.Sc 1141 

CXIX. — The  Interaction  of  Sodium  Hydroxide  and  Benz- 
aldehyde.  By  Chables  Alexandeb  Kohn,  Ph.D.,  B.Sc,  and 
William  Tbantom,  Ph.D.,  B.Sc 1161 

CXX. — The  Ultra-violet  Absorption   Spectrum  of   Proteids  in 

Relation  to  Tyrosine.     By  A.  Wynteb  Blyth     .         .         .116 

Annual  General  Meeting 116 


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JOURNAL 

OF 


THE  CHEMICAL  SOCIETY. 


TRANSACTIONS. 


I. — The   Oxidation  of  Polyhydric  Alcohols  in 
Presence  of  Iron. 

By  Hkhbt  J.  HoBsniAN  FBNTONy  M.A.,  and  Hsnbt  Jacksok, 

B.A.,  B.So. 

Thb  specific  influence  which  ferrous  iron  exerts  on  the  oxidation  of 
certain  hydroxy-acids  has  been  pointed  out  by  one  of  the  authors  in 
several  previous  communications  (Trans.,  1894,  65,  899 ;  Proc.,  1898, 
tc).  In  the  case  of  tartaric  acid,  for  example,  two  atoms  of 
hydrogen  are  removed  from  a  molecule  of  the  acid  with  the  pro* 
duction  of  dihydroxymaleic  acid.  For  the  purpose  of  bringing  about 
this  change,  the  presence  of  ferrous  iron  is  absolutely  essential,  but 
its  proportion  bears  little,  if  any,  relation  to  the  yield  of  the  product, 
the  influence  of  the  iron  being  apparently  of  the  nature  usually 
described  as  ^  catalytic'  The  most  efficient  oxidising  agent  for  the 
porpoee  is  found  to  be  hydrogen  dioxide,  but  a  similar  result  may.be 
obtained  by  chlorine,  potassium  permanganate,  te.,  by  electrolysis, 
and  by  atmospheric  oxygen  in  presence  of  sunlight. 

The  study  of  this  oxidation  process  is  now  being  extended  to  several 
other  hydroxy-acids,  and  Messrs.  Morrell  and  Cross  have  undertaken 
its  application  to  certain  carbohydrates.  Aiming  at  a  complete 
investigation  of  the  reaction  as  regards  various  typical  classes  of 
hydroxy-compounds,  the  present  authors  are  making  a  series  of 
observations  on  the  behaviour  of  various  alcohols,  and  this  com- 
munication deals  with  the  results  which  have  so  far  been  obtained. 
It  will  be  shown  that,  in  the  case  of  all  the  polyhydric  alcohols 
examined,  the  presence  of  ferrops  iron  exerts  a  remarkable  influence 

VOU    LXXV.  Digitized  by€00gle 


2        FENTON  AND  JACKSON  :  THE  OXIDATION  OF 

on  the  ozidation  by  hydrogen  dioxide,  and  that  in  its  absence  the 
results  are  practically  nil. 

In  carrying  out  the  experiments,  a  weighed  quantity  of  the  alcohol 
was  dissolved  in  water,  mixed  with  a  solution  of  ferrous  sulphate 
(corresponding  to  about  ^  ^  i  atom  Fe  *  per  molecule  of  alcohol 
employed)  and  strong  ('20  volume')  hydrogen  dioxide,  previously 
standardised  by  permanganate,  was  gradually  added ;  in  every  case,  a 
blank  experiment  was  made  with  exactly  similar  proportions  and 
under  the  same  conditions,  but  omitting  the  iron.  A  blank  experiment 
was  also  made,  for  comparison,  with  ferrous  sulphate  and  hydrogen 
dioxide  alone ;  5  grams  of  crystallised  ferrous  sulphate  being  dissolved 
in  20  c.a  of  water,  and  about  10  c.c.  of  the  peroxide  gradually  added. 
The  rise  of  temperature  was  very  slight,  and  was  quite  insignificant 
in  comparison  with  that  obtained  in  the  cases  mentioned  below ;  the 
liquid  gave  only  a  brown  colour  or  precipitate  with  Fehling's  solution 
in  the  cold,  without  any  sign  of  reduction,  and  gave  no  indication  with 
Schiff's  rosaniline  test. 

Monhf/dric  AleohoU, 

MethyUo,  ethylio,  propylic,  isopropylic,  and  amylio  alcohols  were 
examined.  The  experiments  were  made  by  taking  10  grams  of  the 
alcohol,  diluting  with  water,  dividing  the  solution  into  two  equal 
parts,  to  one  of  which  0*5  gram  of  crystallised  ferrous  sulphate,  dis- 
solved in  a  little  water,  was  added,  and  each  part  was  then  mixed 
with  the  standardised  hydrogen  dioxide  in  the  proportion  of 
1  mol.  H3O2  to  1  mol.  of  the  alcohol.  No  perceptible  rise  of 
temperature  occurred  in  any  case  either  in  presence  or  absence 
of  iron,  and  the  solutions  gave  practically  no  indication  with  Fehling's 
solution  or  with  SchifP's  rosaniline  test.  The  results  were,  in  fact, 
entirely  negative  under  the  conditions  of  the  experiments,  at  any  rate, 
as  regards  the  production  of  aldehydic  substances,  nor  could  acetone 
be  detected  in  the  case  of  isopropylic  alcohol. 


Ethyhne  Glycol 

On  adding  hydrogen    dioxide    to  a  strong  aqueous  solution    of 
ethylene  glycol,  in  presence  of  a  ferrous  salt,  a  very  sensible  rise  of  tem- 

*  In  the  case  of  tartaric  add,  only  ^^  atom  Fe,  or  leas,  waa  employed  fbr  one 
molecule  of  acid,  bat  in  the  preaent  inveatigation  it  was  found  advisable  to  use  a 
larger  proportion,  and  poasibly  it  may  be  advantageoua  atill  further  to  increase  the 
quantity.  The  reason  for  thia  difference  is  probably  to  be  found  in  the  &ct  that,  in 
tiie  former  caae,  the  ferric  salt  formed  is  almoat  instantly  reduced  at  the  expense  of 
a  portion  of  the  dihydrozymaleic  acid  (Proc.,  May,  1898,  119),  a  result  which 
apparently  is  not  produced  by  the  oxidation  products  here  mentioned. 


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POliTHTBBIC  ALCOHOLS  IN  PRESBNCE  OF  IRON.  3 

peratnre  ooenrSy  and  heat  continues  to  be  evolved  for  a  considerable 
time  after  the  solutions  are  mixed ;  the  product  almost  immediately 
restores  the  colour  to  a  rosaniline  salt  previously  bleached  by  sulphur 
dioxide,  and  reduces  Fehling's  solution  in  the  cold.  Phenylhydrazine 
acetate,  after  a  few  minutes,  gives  a  yellowish-brown,  crystalline  pre- 
ei^tate,  which  continues  to  separate  at  the  ordinary  temperature  for 
some  days.  In  an  exactly  parallel  blank  experiment,  omitting  the 
iron  salt,  there  is  no  perceptible  rise  of  temperature,  and  the  solution 
does  not  reduce  Fehling's  solution  in  the  cold  ;  it  gives,  however,  a 
faint  indication  with  the  rosaniline  test,  and  phenylhydrazine  acetate 
produces  after  a  time  a  small  amount  of  precipitate  somewhat 
resembling  in  appearance  that  above  mentioned,  but  more  disooloured 
and  resinous. 

From  these  results,  it  would  appear  that,  although  glycol  is  very 
slightly  oxidised  by  hydrogen  dioxide  alone,  the  action  is  insignificant 
in  oomparison  with  that  produced  in  presence  of  iron. 

In  order  to  investigate  the  nature  of  the  product  of  oxidation, 
6*2  grams  of  ethylene  glycol  were  dissolved  in  70  c.o.  of  water,  and 
mixed  with  a  solution  of  6*2  grams  of  crystallised  ferrous  sulphate ; 
to  the  mixture  was  gradually  added  65*6  cc.  of  hydrogen  dioxide 
containing  0*0559  H^O^  per  c.c.  The  temperature  began  to  rise  imme- 
diately, and  increased  considerably  after  a  few  minutes.  After 
standing  1^  hours,  a  solution  of  sodium  acetate  was  added  (to  remove 
free  mineral  acid  present  in  the  peroxide),  and  the  solution  was  then 
mixed  with  21*5  grams  of  phenylhydrazine  dissolved  in  50  per  cent. 
acetic  acid.  The  mixture  was  heated  in  a  regulated  water  bath  at 
39*  for  5  hours,  allowed  to  stand  12  hours  at  the  ordinary  tempera- 
ture, and  the  precipitate  was  then  filtered  off,  washed,  and  dried  in 
the  air  ;  the  weight  of  crude  osazone  thus  obtained  was  2*8  grams. 
A  parallel  experiment  was  made  with  a  similar  quantity  of  glycol, 
but  omitting  the  ferrous  salt,  and  using  the  same  quantity  of  phenyl- 
hydrazine,  Ac,  and  heating  exactly  as  before ;  the  precipitate  formed 
in  this  case  weighed  only  0*35  gram. 

The  crude  osazone  obtained  in  the  above  manner  was  first  rubbed 
with  a  very  little  cold  absolute  alcohol,  which  removed  a  little 
resxnons  matter,  and  the  undissolved  yellow  powder  was  twice  recrys- 
tallised  from  hot  absolute  alcohol,  from  which  it  separated  in  yellow, 
transparent  plates,  melting  sharply  at  169*5^,  and  exactly  resembling 
in  every  way  the  product  previously  obtained  from  glycollic  aldehyde 
(Trana.,  1895,  €f7,  774). 

The  substance,  dried  at  100°,  gave  the  following  results  on  analysis. 

0-0900 Bubetancegave 0*2326 CO^and OOiSOHsO ;  C  =  70*49 ;  H  =  5*92. 
Cj^Hj^N^  requires  C  =  70*58 ;  H  =  5*88  per  cent. 

B  2 

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4  FJENTON  AND  JACKSON  :  THE  OXIDATION  OF 

CHINCH*  aHg 
The  sabBtance  is,  therefore,  glyozalofiazone,  Ah'jjV.o  H '  ^^^ 

the  oxidation  product  from  which  it  was  obtained  may  consequently 
be  either  glyecUic  aldehyde  or  glyoxal.     . 

Another  similar  quantity  of  glycol  was  now  oxidised  in  presence  of 
iron  as  before,  the  mixture  well  shaken  with  pure  chalk,  filtered,  and 
the  filtrate  evaporated  to  a  syrup  in  a  vacuum  desiccator ;  absolute 
alcohol  and  a  few  drops  of  ether  were  then  added,  and  the  precipitated 
calcium  salts  filtered  off.  The  solution,  on  again  evaporating  in  a 
vacuum,  left  a  syrup  soluble  in  alcohol  but  nearly  insoluble  in  ether, 
and  showing  all  the  reactions  of  glycollic  aldehyde  ;  it  was  partially 
volatile  with  steam,  reduced  Fehling's  solution  and  ammoniacal  silver 
nitrate  in  the  cold,  and  immediately  answered  Schiff's  rosaniline  test. 

On  shaking  a  strong  aqueous  solution  of  this  syrup  with  excess  of 
freshly  prepared  sodium  hydrogen  sulphite,  no  crystalline  substance 
was  obtained  even  on  allowing  the  mixture  to  stand  for  some  days. 
It  was  thought  that,  on  using  twice  the  proportion  of  hydrogen 
dioxide  (2  mols.),  glyoxal  might  perhaps  be  formed,  but  on  making 
another  similar  experiment  with  this  proportion,  no  compound  with 
the  sulphite  could  be  obtained.  The  result  of  the  oxidation  conducted 
in  the  above  way  is,  therefore,  glycollic  (Udchyde, 

Glycerol. 

When  a  solution  of  glycerol  (1  mol.)  is  mixed  gradually  with 
strong  (20  volume)  hydrogen  dioxide  (1  mol.)  at  the  ordinary  tempera* 
ture,  little,  if  any,  change  takes  place.  No  alteration  of  temperature 
occurs,  and  the  mixture,  even  after  some  days,  gives  very  strong 
reactions  of  hydrogen  dioxide ;  Fehling's  solution,  in  the  cold,  is  not 
reduced,  and  the  addition  of  phenylhydrazine  acetate  merely  gives  rise 
to  an  evolution  of  gas  owing  to  the  presence  of  hydrogen  dioxide,  and 
there  is  a  slight  precipitation  of  resinous  matter.  When,  however,  an 
exactly  parallel  experiment  is  made  with  the  previous  addition  of  a 
small  quantity  of  ferrous  sulphate  in  solution,  a  very  powerful  action 
results.  The  peroxide  is  now  consumed  almost  immediately,  and  the 
temperature  rises  very  considerably,  in  fact,  if  the  peroxide  is  added 
quickly,  and  the  solutions  are  strong,  the  vessel  becomes  almost  too 
hot  to  be  held  in  the  hand.  The  solution,  when  cold,  now  strongly 
reduces  Fehling's  solution  in  the  cold,  immediately  answers  SchifiE's 
rosaniline  test,  and  if  it  is  mixed  ^vith  phenylhydrazine  acetate,  a 
bulky,  yellowish-brown,  crystalline  precipitate  begins  to  separate  at 
the  ordinary  temperature,  and  continues  to  do  so  for  several  days. 

If  a  ferric  salt  be  substituted  for  ferrous  in  the  above  experiment, 
the  result  is  entirely  negative.    In  order  to  investigate  the  nature  of 

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POLTHTBRIG  ALCOHOLS  IN  PBSSKNCE  OF  IRON.  5 

I 
I 

the  prodoet,  10  grams  of  glycerol,  diluted  with  an  equal  bulk  of  water,  I 

was  mixed  with  a  solution  of  I  gram  of  crystallised  ferrous  sulphate,  \ 

and  45  c.c.  of  hydrogen  dioxide  (of  the  before-mentioned  strength) 
was  slowly  added,  the  rise  of  temperature  being  moderated  by 
immersing  the  Teasel  in  cold  water.  Sodium  acetate  and  20  grams  of 
phenylhydrazine,  as  acetate^  were  then  added  as  before,  and  the 
mixture  was  left  for  some  days  at  the  ordinary  temperature ;  the  pre- 
cipitate formed  was  then  wadied,  drainedi  and  dried  in  the  air.  It 
weighed  6-2  grams.  After  crystallising  from  50  per  cent,  alcohol, 
and  then  twice  from  benzene,  the  substance  was  obtained  in  beautiful, 
golden,  transparent  prisms  which  melted  at  130 — 131^.  The  sub* 
stance,  dried  at  100%  gave  the  following  results  on  analysis. 

L  01185  gave  0-2920  CO,  and  0-0630  H^O. 

n.  0-0760    „  14-5c.c.nitrogenat22°and764mm.  C  =  67-22;H  =  6-90;N-2116. 
CijH^^N^O  requires  0«6716  ;  H-6-97  ;  N«  20*89  per  cent. 

This    product,    therefore,    exactly    coincides    with   glyeeroscuane, 
OH-CHj-CINaH-O^Hg         y^^  ^^  obtained  by  Fischer  and  Tafel 

from  <  glyceroee '  {Ber.,  1887, 20, 1088,  and  1888, 21,  2634),  by  Piloty 
and  Ruff  from  dihydroxyacetoxime  (.6^.,  1897,  30,  1662),  and  by 
Piloty  from  dihydroxyacetone  (Ber.,  1898,  81,  3165). 

The  oxidation-product  here  obtained  may,  therefore,  be  dihydroxy- 
acetone, C0<^^;^5,  glyceraldehyde,  OH-CH<^|[^^,  or,  like 

Fischer's  *  glyceroee,'  a  mixture  of  these  two. 

'Olyoeroee,'  obtained  by  the  interaction  of  lead  glyceroxide  and 
bromine,  was  shown  to  consist  for  the  greater  part  of  dihydroxy- 
acetone ;  this  was  proved  by  the  large  yield  of  trihydroxyisobutyric 
add  obtained  by  the  hydrogen  cyanide  reaction  {Ber.,  1889,  22,  110) 
and  was  later  confirmed  by  Piloty  {loe.  eii.,  3163)  from  the  yield  of 
dihydroxyacetoxime.  The  presence  of  glyceraldehyde  was  probable 
bom  the  fact  that»  after  separation  of  the  trihydroxybutyric  acid  as 
eakiam  salt,  lead  acetate  gave,  in  the  mother  liquor,  a  flocculent  pre- 
cipitate insc^uble  in  hot  water  and  in  dilute  acetic  add,  differing  in 
these  respects  from  the  trihydroxyisobutyrate.  The  quantity  obtained 
by  Fischer  and  Tafel  was  not  suffident  for  comparison  with  '  erythro- 
glndc  add,'  and,  moreover,  the  properties  of  this  latter  acid  are  not 
at  all  characteristie. 

A  sharp  distinction,  however,  between  trihydroxyisobutyric  acid  and 
eijthrogludc  acid  exists  in  the  fact  that  the  neutral  salts  of  the 
former  are  not  precipitated  by  normal  lead  acetate. 

The  product  obtained  in  the  present  instance  was  further  examined 
b  the  following  way.    About  50  grams  of  glycerol  were  oxidised  in 

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6  PENTON  AND  JACKSON  :  THE  OXIDATION  OF 

presence  of  iron  in  the  manner  described  above,  and  the  mixture,  when 
cold,  was  well  stirred  with  excess  of  barium  carbonate ;  the  solution, 
after  filtration,  was  evaporated  to  a  small  bulk  by  distillation  under 
greatly  diminished  pressure  at  50^,  concentrated  to  a  syrup  in  a  vacuum 
desiccator,  and  then  mixed  with  several  times  its  volume  of  absolute 
alcohol  and  a  little  ether.  After  being  allowed  to  stand,  it  was  filtered 
from  barium  and  iron  salts,  the  filtrate  again  allowed  to  evaporate  in 
a  vacuum  desiccator,  and  the  residue,  dissolved  in  a  little  absolute 
alcohol,  was  mixed  with  about  three  times  its  volume  of  anhydrous 
ether ;  the  precipitate  was  then  allowed  to  settle,  and  the  ether- 
alcohol  solution  evaporated  in  a  vacuum  desiccator  as  before. 
No  signs  of  crystallisation  could  be  observed,  however,  even  after 
repeating  the  alcohol-ether  treatment  and  allowing  the  syrup  to  remain 
for  several  days  in  the  vacuum,  neither  oould  crystallisation  be  brought 
about  by  cooling  or  by  stirring  with  a  drop  of  water.  Piloty  {Ber., 
1898,  31,  3164)  obtained  crystallised  dihydroxyacetone  (from  dihy- 
droxyacetoxime) ;  and  Wohl  {ibid,,  2394),  from  the  acetal  of  glycer- 
aldehyde,  obtained  crystals  corresponding  in  composition  to  the 
aldehyde.  Wohl's  crystalline  compound,  however,  was  shown  by  the 
cryoscopic  method  to  have  a  ^  double '  formula,  becoming  '  single ' 
when  kept  for  some  time  in  aqueous  solution. 

In  the  present  <!ase,  therefore,  it  was  not  certain  that  crystallisation 
should  be  expected  if  the  substance  is  glyceraldehyde,  but  the  absence 
of  crystallisation  may  very  probably  be  due  to  tiie  presence  of 
impurities  such  as  traces  of  barium  or  glycerol,  which,  by  the  above 
treatment,  might  not  be  wholly  removed.  In  order  to  attack  the 
problem,  therefore,  the  method  employed  by  Fischer  and  Tafel  was 
followed  j  for  this  purpose,  the  purified  syrup  obtained  in  the  manner 
above  described  was  dissolved  in  100  c.c.  of  water,  and  the  reducing 
power  of  the  solution  estimated  by  Fehling's  solution*  The  quantity 
available  corresponded  to  6*2  grams  of  glucose ;  this  was  mixed  with  7 
grams  of  anhydrous  hydrogen  cyanide  and  heated  in  a  stoppered  bottle, 
in  aregulated  bath, at  60°for  12  hourB,and  then  for  12  hours  more  at  60**. 
The  light  brown  solution  was  then  evaporated  somewhat  in  a  vacuum  to 
remove  free  hydrogen  cyanide,  the  mixture  placed  in  a  freezing  mixture, 
saturated  with  dry  hydrogen  chloride,  and  allowed  to  remain  for 
12  hours  at  0%  and  for  2  days  more  at  the  ordinary  temperature; 
it  was  then  evaporated  as  completely  as  possible  on  a  water  bath,  the 
residue  dissolved  in  about  200  c.c.  of  water,  45  grams  of  barium 
hydroxide,  dissolved  in  hot  water,  added,  and  the  mixture  heated  on  a 
water  batL  Alter  a  few  minutes,  a  pale  yellow,  fiocculent  precipi- 
tate separated  which  was  collected  while  hot,  washed,  and  treated  with 
a  slight  excess  of  hot  dilute  sulphuric  acid  ;  the  filtered  solution  was  very 
cautiously  treated  with  baryta-water  to  remove  the  excess  of  sulphuric 

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FOLYHTBBIC   AI.COHOLS  IN   PRBSENCK  OF  IRON.  7 

add,  filtered,  md  the  filtrate  shaken  with  pare  precipitated  calciom  car- 
bonate. The  clear  liquid  thus  obtained  was  concentrated  and  allowed 
to  rtand  for  4  days,  but  there  were  no  signs  of  crystallisationi  so  that 
trihydioxybatyric  acid  appears  to  be  either  absent,  or  present  in  small 
q[aAntity  only.  The  solution  of  calcium  salt  was  then  decolorised 
with  a  little  animal  charcoal,  and  a  solution  of  normal  lead  acetate 
added ;  a  white,  flooculent  precipitate  was  produced  which  appeared  to 
be  insDluble  in  hot  water  or  in  acetic  acid.  This  precipitate  was  well 
washed  with  hoc  water  and  dried  at  160^. 

L  0-2693  gave  02303  PbSO^.     Pb  =  6067  per  cent, 
n.  01190    „    01060  PbSO^.    Pb  =  60-82 

Lamparter  {Amudm^  184,  261)  obtained  erythroglucic  acid  by  oxida- 
tion of  erythritol  with  nitric  acid,  and,  by  precipitation  of  the  free 
acid  by  excess  of  lead  acetate,  prepared  the  lead  salt  which,  when 
dried  at  160°,  gave  Pb  »  61  '3  per  cent.  The  salt  would  appear,  there- 
fore, to  have  the  composition  G^Hi^PbOg  (the  lead  replacing  in  a 
hydroiyl  as  well  as  the  carbozyl  group),  for  which  theory  requires 
Pb=60-70  per  cent. 

Another  portion  of  the  ether-alcohol  solution,  prepared  as  before, 
was  mixed  with  the  calculated  quantity  of  hydrozylamine  in  alcoholic 
sdiition,  distilled  to  a  small  bulk  under  greatly  reduced  pressure,  and 
kept  in  a  vacuum  desiccator ;  the  syrup  which  was  left  showed  praotic- 
ally  no  signs  of  crystallisation,  even  after  long  standing,  stirring,  dEc. 
From  the  above  results,  it  appears  probable  that  the  product  of  oxi- 
dation here  obtained  is  chiefly,  if  not  entirely,  glyceraldehyde. 

Erythritol, 

Experiments  with  this  substance  were  made  in  exactly  the  same 
manner  as  in  the  previous  cases,  and  here  again  it  was  found  that 
practically  no  actiou  occurs  in  absence  of  ferrous  iron ;  if  present, 
however,  there  is  energetic  oxidation  with  considerable  evolution  of 
heat.  The  product  strongly  rednces  Fehling's  solution  on  warming, 
and  restoTOB  the  colour  to  a  rosaniline  salt  bleached  by  sulphur 
dioxide.  Phenylhydraadne  acetate,  after  a  short  time,  gives  a  beautiful, 
golden,  flooculent  precipitate,  which  increases  in  quantity  on  heating. 

Ten  grams  of  erythritol  was  dissolved  in  300  cc.  of  water,  mixed  with 
5  grams  of  crystallised  ferrous  sulphate,  and  50  cc.  of  hydrogen  dioxide 
abwly  added  as  before ;  to  the  mixture,  25  grams  of  phenylhydraxin 
as  aeetate  was  then  added,  and  the  whole  allowed  to  remain  for  24  hours 
at  the  ordinary  temperature.  The  precipitate,  after  being  collected, 
washed,  drained,  and  dried  in. the  air,  weighed  3*7  grams.  The  mother 
Uqaor  was  then  heated  on  a  water  bath  for  \\  hours,  and  the  precipitate 

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8  FENTON  AND  JACKSON  :  THE  OXIDATION  OF 

collected,  washed,  and  dried  as  before  ;  it  weighed  3*3  grams,  so  that 
the  total  yield  was  aboat  7  grams. 

For  analysis,  the  first  product  was  selected,  since  that  obtained  by 
heating  the  mother  liqaor  was  somewhat  discoloured  and  looked  leas 
pura  It  was  first  heated  with  a  large  volume  of  water,  in  which  it 
slowly  dissolved,  and  the  filtered  solution  deposited  a  golden,  floccolent 
precipitate  on  cooling ;  this  was  collected,  air-dried,  and  twice  re- 
crystallised  from  hot  benzene,  from  which  it  separated  in  golden, 
microscopic  needles. 

After  being  dried  at  100°,  it  melted  sharply  at  167°,  and  gave  the 
following  numbers  on  analysis. 

00920 gave  0-2178  00^  and  0-0496  H,0.     C  =  64-56 ;  H  =  6-91. 
Erythrosasone,  Oj^H^gN^Oj,  requires  0  =  64*43  ;  H  =  6*04  per  cent. 

From  the  good  yield  of  osazone  obtained  in  this  experiment,  the 
authors  are  encouraged  to  attempt  the  direct  isolation  of  the  oxidation 
product,  and  experiments  will  shortly  be  made  in  this  direction. 

Manntiol. 

In  this  case,  again,  the  presence  of  ferrous  iron  exerts  a  remarkable 
influence  in  bringing  about  the  oxidation  by  hydrogen  dioxide ;  a  very 
considerable  rise  of  temperature  occurs,  and  the  mixture,  when  cold 
gives  an  almost  immediate  precipitate  with  phenylhydrazine,  and  after 
separation  of  the  iron,  strongly  reduces  Fehling's  solution  on  warming. 
In  absence  of  ferrous  iron,  no  such  changes  take  place. 

Twenty  grams  of  pure  recrystallised  mannitol  were  dissolved  in 
100  c.c.  of  water,  mixed  with  5  grams  of  crystallised  ferrous  sulphate 
and  60  c.c.  of  hydrogen  dioxide  in  the  same  manner  as  before.  The 
solution,  after  cooling,  was  made  just  alkaline  with  sodium  carbonate, 
then  acidified  with  acetic  acid,  and  to  the  mixture  6  grams  of 
phenylhydrazine  as  acetate  were  added.  The  separation  of  a  yellow 
precipitate  began  after  about  1  minute,  and  was  allowed  to  continue 
for  1  hour ;  it  was  then  collected,  drained  with  the  aid  of  the  pump, 
washed,  and  allowed  to  dry  in  the  air.  The  crude,  orange-coloured 
substance,  which  weighed  12-5  grams,  was  purified  by  triturating  it 
with  a  little  acetone,  draining  with  the  pump,  and  crystallising  from 
boiling  water ;  the  filtered  solution,  on  cooling,  deposited  a  yellowish- 
white,  crystalline  precipitate,  which  was  recrystallised  from  hot  60  per 
cent,  alcohol,  and  twice  again  from  hot  water  with  the  addition  of  a 
little  animal  charcoal.  In  this  way,  the  product  was  obtained  in  the 
form  of  almost  white,  crystalline  plates,  which  turn  yellow  at  about 
195°  and  melt  fairly  sharply  at  1 97 — 198°.  For  analysis,  the  substance 
was  dried  at  100°. 


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POLYHYBRIC  ALCOHOLS   TN  PBESENCE  OF  IKON.  9 

L  01206  gave  0-2346  COj  and  00710  H^O.    0  =  63-29  ;  H  =  6-67. 
II.  0-1020  gave  93  c.c.  nitrogen  at  17°  and  766  mm.     N=  10*66. 
Maonoae  hydrazone,  C^H^gN^Os,  requires  C  »  63-33 ;  H  =  6*66 ;  N  » 10-39  per  cent. 

Direct  Preparation  of  Mannoee  from  [Mannitol. — As  the  yield  of 
hydiazone  obtained  in  the  manner  just  described  appears  to  be 
considerably  superior  to  that  which  results  from  the  oxidation  of 
mannitol  by  nitric  acid,  it  became  a  matter  of  interest  to  ascertain 
whether  the  sugar  could  be  prepared  directly  from  the  mixture 
obtained  from  oxidation,  without  previously  isolating  the  hydrazone. 
Fifty  grams  of  mannitol  were  dissolved  in  a  small  quantity  of 
water,  mixed  with  a  solution  of  ferrous  sulphate,  and  160  c.c.  of 
hydrogen  dioxide  added  as  previously  described.  The  mixture  was 
then  treated  with  excess  of  freshly  precipitated  barium  carbonate, 
filtered,  the  clear  solution  evaporated  to  a  small  bulk  at  about  60^  under 
a  pressure  of  about  30  mm.,  and  the  concentration  then  continued 
in  a  vacuum  desiccator  at  the  ordinary  temperature  until  a  thick 
syrup  remained.  This  was  treated  with  about  ten  times  its  volume  of 
absolute  alcohol,  filtered,  and  an  excess  of  anhydrous  ether  added  to 
the  clear  filtrate ;  this  caused  the  separation  of  a  white,  flocculent 
mass,  which,  on  standing,  collected  to  a  light  yellow  syrup.  After 
pouring  off  the  liquid,  the  syrup  was  dissolved  in  a  very  small  quantity 
of  water,  the  solution  exposed  in  a  vacuum  desiccator,  and  the  syrupy 
residue  thus  obtained  was  rubbed  with  absolute  alcohol  and  ether, 
when  it  was  converted  into  a  pasty  mass,  which  became  a  greyish- 
whitOy  amorphous  gum  when  kept  in  a  vacuum  over  sulphuric  acid. 
0*36  gram  of  this  product  was  dissolved  in  a  little  water,  mixed  with 
0-6  gram  of  phenylhydrazine  as  acetate,  and  the  mixture  allowed  to 
stand  for  one  hour ;  a  little  absolute  alcohol  was  then  added  and  the 
precipitate  collected  on  a  weighed  filter  and  dried  at  100°.  The  weight 
of  hydraaone  obtained  was  0-66  gram. 

Wt.  of  substance  :  wt.  of  hydrazone  obtained  =  1 :  1*66. 
Theory  requiring,  mannose  :  hydrazone  » 1  :  1*63. 

The  result,  in  fact,  appears  to  be  mannose  in  a  pure,  or  nearly  pure, 
sUte. 

Dtdcitol, 

Sxaetly  similar  phenomena  are  observed  when  this  substance  is 
oxidised  by  hydrogen  dioxide  in  presence  of  ferrous  iron,  the  blank 
test  giving  negative  results.  Ten  grams  of  duldtol  dissolved  in 
SOO  CO.  of  water,  was  mixed  with  6  grams  of  crystallised  ferrous 
mdphate  and  40  c.o.  of  hydrogen  dioxide  added.  After  cooling,  20 
grams  of  phenylhydrazine  as  acetate  was  added,  the  mixture  heated  on 

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10     OXIDATION  OV  POLTHYDRIO  ALCOHOLS  IN  PRESENCE  OF  IROK. 

a  water  bath  for  one  hour,  and  the  yellowish^  flocculent  precipitate  thus 
formed,  when  collected,  washed,  and  air-dried,  weighed  3-8  grams. 

The  crude  osazone  was  rubbed  with  a  little  cold  absolute  alcohol,  to 
remove  resinous  matter,  and  then  twice  recrystallised  from  hot 
absolute  alcohol ;  the  beautiful  yellow  leaflets  thus  obtained  were  dried 
a  100°  and  analysed. 

0-1030  gave  0-2290  CO,  and  00684  H^O.    C « 60-63 ;  H » 6*29. 
CigHj^Np^  requires  0*60-33 ;  H»6'15  per  cent. 

The  substance,  when  quickly  heated,  melted  sharply  at  206°,  and 
appears,  therefore,  to  be  identical  with  that  which  Fischer  and  Tafel 
obtained  by  oxidising  duldtol  with  bromine  {Ber.,  1887,  20,  3390). 

Sorbitol. 

Only  a  small  quantity  of  this  substance  was  available,  but  the  results 
obtained  were  exactly  analogous  to  those  previously  recorded.  In 
presence  of  iron,  heat  was  evolved  and  the  solution  then  strongly 
reacted  with  phenylhydrazine,  the  blank  experiment  without  iron 
showing  practically  no  result. 

0*7  gram  of  sorbitol  was  dissolved  in  water,  mixed  with  a  solution 
of  0-3  gram  of  ferrous  sulphate,  and  10  c.c.  of  hydrogen  dioxide 
added ;  on  adding  phenylhydrazine  acetate  and  heating  the  mixture 
on  a  water  bath  for  one  and  a  half  hours,  an  osazone  was  obtained, 
which,  after  being  washed,  and  recrystallised  from  ethylic  acetate, 
melted  sharply  at  203°,  and  closely  resembles  glucosazone. 

On  analysis, 

0-1190  gave  0-2625  00^  and  00672  H^O.     C«6019 ;  H«6-28. 
CigH^N^O^  requires  C»  60-33  ;  H  =  6-16  per  cent. 


Oxtdation  in  Presence  of  Sunlight, 

In  the  case  of  tartaric  acid,  it  was  shown  {Brit,  A$boo,  Bepcri,  1895), 
that  the  oxidation  to  dihydroxymaleic  acid  may  be  brought  about  by 
atmospheric  oxygen  in  presence  of  ferrous  iron  on  exposure  to 
sunlight;  whilst  in  the  absence  of  ferrous  iron,  or  in  the  dark, 
practically  no  oxidation  occurs.  That  the  result  was  not  due  to 
atmospheric  hydrogen  dioxide  or  ozone  was  shown  by  using  air 
previously  purified  by  means  of  potassium  iodide.* 

It  is  now  found  that  a  similar,  although  less  rapid,  result  may  be 
produced  in  the  cases  of  glycol,  glycerol,  and  erythritol.  The  oxidation 
products  obtained  with  these  substances  in  the  manner  described, 
all  quickly  restore  the  colour  to  a  rosaniline  salt  previously  bleached 

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id-ALDEHTOOPROPIONIC  ACID,  ETC.  ll 

by  sulphur  dioxide,  so  that  this  test  affords  a  delicate  means  of  in- 
dicaUng  the  formation  of  such  products.  The  experiments  were  made 
in  the  following  way. 

A  eolation  of  the  alcohol  was  divided  into  three  parts.  To  1  and  2 
a  litUe  ferrous  sulphate,  in  solution,  was  added  and  3  was  left  blank ; 
1  was  kept  in  a  dark  cupboard,  and  2  and  3  were  exposed  to  sunlight 
for  some  hours.  The  three  samples  were  then  tested  with  the  rosani- 
line  solution,  and,  in  the  case  of  each  of  the  above-named  alcohols,  a 
strongly  marked  coloration  was  produced  in  2,  that  is,  in  the  one 
exposed  to  sunlight  in  presence  of  iron,  but  practically  none  was 
obtained  in  1  or  in  3. 

In  the  case  of  mannitol,  dulcitol,  dpc.,  the  results  are  uncertain,  since 
the  rosaniline  test  is  inapplicable,  and  the  characteristic  reactions  of 
the  products  of  oxidation,  such  as  with  phenylhydrazine,  are  scarcely 
delicate  enough  for  the  purpose. 

The  greater  part  of  the  expense  incurred  in  carrying  out  this  and 
several  previous  investigations  has  been  defrayed  from  grants  kindly 
awarded  by  the  Government  Grant  Committee  of  the  Eoyal  Society. 


II. — fi'Aldehydopropionic  Add,  CHO-OHa-CHg-COOH, 
arbd  fi'Aldehydoisohutyric  Add,  OHO-CH2-CH(CH3)'COOH. 

By  W.  H.  Pb&kih,  jun.,  and  C.  H.  G.  Spbankling. 

Some  time  since  (Trans.,  1896, 60,  162),  a  paper  was  published  by  one 
of  us  in  conjunction  with  Messrs.  W.  H.  Bentley  and  E.  Haworth 
which  had  for  one  of  its  objects  the  discovery  of  a  method  for  intro- 
ducing tbe  group  'GH^'CH^'OH  into  organic  substances,  a  synthetical 
process  which,  if  it  could  be  easily  carried  out,  would  be  very  valuable 
as  a  means  of  forming  ring  compounds.  It  was  found  that  the  action 
of  glycol  ehlorhydrin,  Cl'CHij'CHg'OH,  on  the  sodium  compounds  of 
sabstanees  like  ethylic  acetoacetate,  ethylic  malonate,  and  their 
derivatives,  did  not,  except  in  isolated  cases,  yield  the  desired  result ; 
ultimately,  however,  a  method  was  devised  which  in  the  few  cases  tried 
gave  fairly  satisfactory  results,  and  which  may  be  briefly  stated  in  the 
form  of  an  example  thus. 

/3-Bromethyl  phenyl  ether,G5Hg«0*GH2'GH3Br,wasprepared  by  acting 
on  sodium  phenoxide  with  ethylene  bromide,  and  this,  when  digested 
wiihthe  sodium  derivative  of  ethylic  methylmalonate,  yielded  ethylic 
y-pifaenoxyethylmethylmalonate , 

CeH,-G-CH,-CH,-0(OH3)(COOG2H5)  2. 
The  add  corresponding  to  this  ethereal  salt,  when  heated  at  100^,  loses 

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12     PERKIN  AND  SPRANKLING  :  /9-ALDEHYDOPBOPIONIC  ACID 

one  molecule  of  carbon  dioxide  with  formation  of  y-phenozyethyl- 
methylacetic  acid,  C^H5-0-CHj-0H,-CH(CH8)-COOH,  from  which 
hydrobromic  acid  eliminates  the  phenyl  group  and  forms  y-bromethyl- 
methylacetic  acid,  CH2Br*OH3-CH(CH3)«OOOH.  This  brom-acid  when 
boiled  with  sodium  carbonate,  gives  the  sodium  salt  of  hydrozyethyl- 
methylacetic  acid,  OH-CH2«OH2-CH(CH3)*COONa,  from  which,  on 

acidifying,    methylbutyrolactone    Y^        ^  Y        **8^    ig    at     once 

obtained.  When  this  method  was  tried  in  more  complicated  synthetical 
experiments,  it  did  not  work  well,  partly  owing  to  the  number  of 
operations  involved,  but*  principally  on  account  of  the  smallness  of  the 
yield  obtained  in  some  of  these  operations.  For  these  reasons,  experi- 
ments were  made  with  a  view  to  discover  a  more  direct  method,  and 
ultimately  we  found  in  hromaceUUf  (C2H50)2CH'CH2Br,  a  substiince 
which  seems  likely  to  answer  the  purpose. 

Bromacetal  reacts  readily  with  the  sodium  derivative  of  ethylio 
malonate,  yielding  ethylic  cteetalmaloncUe  according  to  the  equation 

(C,H50)30H-CH,-CH(COOC,Hj),  +  NaBr. 

This  ethyiic  salt,  which  distils  without  decomposition  at  151 — 164^ 
(15  mm.),  yields,  on  hydrolysis,  the  corresponding  (iceUUmalanie  add^ 
(C2H5O)2CH-CH2-0H(COOH)2,and  this,  when  heated  with  water  at  180*^ 
is  decomposed  into  alcohol,  carbon  dioxide,  and  fi-aldehydoprapumie 
acid,  {CjH50)2CH-CHj-CH(COOH)2  +  H^O  -  CHO-OHj-  CH,-  COOH  + 
2C2Hg'OH  +  COj.  j3-Aldehydopropionic  acid  is  a  new  and  very  inter- 
esting substance,  since  it  is  the  "  half-aldehyde  "  of  succinic  acid  and 
belongs  to  the  elate  of  aldehyde  acids  of  which,  iso  far,  very  few  have 
been  prepared.  Its  properties  show  that  it  is  a  true  aldehyde,  and  not 
a  hydroxymethylene  compound  of  the  formula 
CH(0H):0H-CH2-000H, 
it  therefore,  does  not  belong  to  the  class  of  substances  which  Olaisen 
has  investigated  with  such  brilliant  results.  Aldehydopropionic  acid  is 
an  almost  colourless  liquid  which  reduces  Fehling's  solution  and  gives  a 
violet  coloration  with  a  solution  of  rosaniline  hydrochloride  decolorised 
by  sulphurous  acid.  It  is  slowly  oxidised  in  contact  with  air,  rapidly 
by  nitric  acid,  with  formation  of  succinic  acid,  and  when  reduced  with 
sodium  amalgam  it  yields  buiyrolactane^ 

CHO-CHj-OHg-OOOH-OH-CHg-OHg-CHj-COOH-  9^'^^*  ^. 

When  boiled  with  caustic  soda  solution  in  a  flat  basin,  aldehydopropionic 
acid  undergoes  a  most  interesting  change,  yielding  small  quantities  of 
terephthcUie  aeid,  the  dihydroterephthalic  acid,  which  may  be  assumed 
to  be  the  first  product  of  the  condensation,  being  oxidised  to  ter»- 

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AND  /9-ALDKHTDOISOBUTTBIC  ACU>.  13 

phthalie  add  hj  the  action  of  the  air, 

CHO-CHj-CHjCOOH  CHCHjCOOOH 

oooh-  chj-  ch,-  cho        -    ooohc  •  ch,-  ch 

ch-oh:c-cooh 
=    oooh-c-ch:ch 

and  this  is,  so  far,  the  only  experiment  which  has  been  instituted  with 
the  object  of  testing  the  valne  of  aldehydopropionic  acid  i^  conden 
sation  experiments. 

The  action  oi  bromaoetal  on  sodium  compounds  is  probably  a  general 
onoi  since  we  have  found  that  the  reaction  proceeds  equally  well  when 
the  sodium  derivatiYe  of  ethylic  methylmalonate  is  substituted  for  that 
of  ethylic  malonate  in  the  above  experiments. 
The  eihylie  €teetalmethylmalanale, 

(C2H50),CH-CH,-C(CH3)(C(X)C2H,)2, 
thus  obtained  yields  aeeUdmethyhnalonie  acid, 

(C2H50)2-CH-CHj-C(CHg)(COOH)j, 
on  hydrolysifl,  and  this,  when  heated  with  water  at  180^,  is  converted 
into  /3-aldehydoisobutyricacid,  CH0-CHg-CH(CF8)-CX)0H,  a  Uquid  acid 
which,  on  oxidation,  yields  methyl  succinic  acid, 
C00H-CH,-CH(CH3)-C00H. 
Further  experiments  on  the  action  of   bromacetal  on  the  sodium 
compounds  of  ethereal  salts  are  in  progress.     It  should  be  mentioned, 
in  conclusion,  that  C.  Harries  (Ber.,  1898, 31, 42)  obtained  a  substance 
which  is  probably  the  methylal  of  the  half-aldehyde  of  succinic  acid, 
(CHgO)jCH'CH2-CHj-COOH,  by  the  action  of  sodium  hypobromite  on 
levulin  methylal,  (OH30)2CH-CH3'GH,*CO-GH3,    but   he  does   not 
H^pear  to  have  further  investigated  this  substance. 


Aeiicn  qf  Bramaceial  on  the  Sodium  Derivative  of  Ethylic  malonate. 
Formaiuyn  of  Ethylic  AcetalmaU(mate,(0fifi)filI'Cn^'CR{COOC^U^\. 

Ethylic  aoetalmalonate  is  conveniently  prepared  as  follows. 
Sodium  (14*2  grams)  is  dissolved  in  absolute  alcohol  (170  grams)  and 
the  scdution,  while  still  warm,  is  mixed  with  ethylic  malonate  (100 
grams)  and  bromacetal  (80  grams)  and  the  mixture,  inclosed  in  sealed 
tubes,  is  heated  at  130^140°  for  4  hours;  when  as  much  alcohol  as 
possible  has  been  removed  from  the  product  by  distillation  on  the  water 
bath,  water  is  added  to  the  residue  and  the  precipitated  oil  extracted 
several  times  with  ether.  The  ethereal  solution  is  washed,  well  dried 
over  calcium  chloride,  the  ether  distilled  off,  and  the  residual  oil  f rac- 
tionated  under  reduced  pressure  (16  mm.).  More  than  half  passes  over 
below  145*^  and  consists  of  a  mixture  of  unchanged  ethylic  malonate 
tad  bromaoetal,  whilst  the  fraction  distilling  between  145°  and  165° 


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14     PEBKIN  AND  SPRANKLIN6 :   /9-ALDEHTDOPBOPIONIC  ACID 


;o 


contains  the  ethylio  aoetalmalonate.  The  oil  boiling  below  146^ 
(15  mm.),  and  which  was  assumed  to  contain  about  50  per  cent,  of 
bromacetal,  was  again  heated  in  sealed  tubes  with  the  caleolated 
quantity  of  the  sodium  derivative  of  ethylio  malonate,  the  temperature, 
however,  being  now  allowed  to  rise  to  160^ 

In  this  way,  practically  the  whole  of  the  bromaeetal  was  converted 
into  crude  ethylic  acetalmalonate  boiling  at  145 — 166°  (15  mm.),  and 
from  this  fraction  the  almost  pure  ethereal  salt  could  be  obtained  by 
repeated  fractionation  as  a  colourless  oil  of  a  peculiar  and  not  unplea- 
sant odour,  and  boiling  at  151—154''  (16  mm.),  or  at  166—168''  (at 
26  mm.).     Analysis.* 

01821  gave  0-3714  CO2  and  01418  H,0.    C=55-62 ;  H-8-65. 
01640     „     0-3360  CO3    „    0-1282  H^O.     0=55-87 ;  H- 867. 
(02H5O)j0H-0H,-CH(COOO2H5)2  requires  0  =  56-50;  H  =  869  per  cent. 


Acetalmalomc  Acid,  (C2H50)3CH-CH2-CH(C(X)H)3. 

Acetalmalonic  acid  is  obtained  by  hydrolysing  its  ethereal  salt 
with  alcoholic  potash,  but  the  operation  has  to  be  carefully  performed, 
since  prolonged  boiling  with  the  alkali  decomposes  the  acid  with 
elimination  of  the  group  *CH2*CH(OC2H5),  and  formation  of  malonio 
acid.  It  is  not  clear  how  this  decomposition  takes  place,  but  there  can 
be  no  doubt  as  to  the  formation  of  malonic  acid,  since,  in  one  instance, 
when  a  quantity  of  this  acid  was  obtained  melting  at  131°,  an  analysis 
was  carried  out  with  the  following  results. 

0-2687  gave  03480  COg  and  00972  H,0.     0= 35-32 ;  H  =  426. 
0Hj(C00H)2  requires  0  =  34-63;  H«3-86  per  cent. 

It  was  very  soluble  in  water,  and  when  heated  decomposed  with 
evolution  of  carbon  dioxide  and  formation  of  acetic  acid. 

If,  however,  the  action  of  the  potash  is  only  allowed  to  proceed  for 
a  short  time,  hydrolysis  takes  place  normally,  and  a  good  yield  of 
acetalmalonic  add  is  obtained.  After  many  experiments,  we  found 
that  the  following  process  gave  the  best  results.  Ten  grams  of  the 
pure  ethereal  salt  is  mixed  with  a  solution  of  6  grams  of  pure  potash 
in  alcohol,  and  the  mixture  heated  on  the  water-bath  for  10  minutes, 
the  alcohol  is  then  rapidly  driven  off  on  the  water -bath  and  the  cold 
residue  mixed  with  an  excess  of  dilute  sulphuric  acid  and  extracted 
repeatedly  with  ether.  The  ethei-eal  solution,  after  drying  and 
evaporating,  deposits  a  thick  oil  which  shows  no  sign  of  orystalliBin^y 
even  after  standing  for  some  days  over  sulphuric  acid  in  a  vacuum.    On 

*  The  numbers  obtained  are  slightly  lov,  on  accoant  of  the  oil  containing  traces 
of  bromine,  which  it  was  found  impossible  to  remove  by  fhustionation. 


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AN]>    /3-ALDEHTD0IS0BUTtlEtIC  ACTO.  15 

ifiilysis^^it  gave  numbers  agreeing  approzimatelj  with  those  required 
{oraoetahnalomc  acid. 

L  0115O  gave  0-2040  CX)2  and  00722  H^O.    0=4915  ;  H-  697. 

n.  01779  „  0-3177  OOjj  „  01200  H^O.  0  =  48-72;  H  =  7-47. 
ffl.  0-1974  „  0-3529  OOj  „  01227  H,0.  0  =  48-75 ;  H  =  6-91. 
IV.  01537  „  0-2719  002  „  00915  H^O.  0  =  4826  j  H  =  6-61. 
(000H)^CH.-CH,'OH(OO2H5)j  requires  0  =  4905  ;  H«:7-27  per  cent. 

Sth&rmU. — Aeetalmalonic  add  is  very  soluble  in  water,  and  if  the 
aqueous  solution  is  neutralised  with  ammonia,  and  silver  nitrate  added, 
a  dense,  white  precipitate  of  the  silver  salt  is  precipitated,  which,  after 
washing  first  with  water  and  then  with  alcohol  and  ether,  gave  the 
following  results  on  analysis. 

0-2177  gave^  on  ignition,  0109  2  Ag.   Ag  =  50*16. 
(C^50),OH'CH8' 0H(000Ag)3  requires  Ag  =  49-79  per  cent. 

JDistilUuion  qf  AeeUUmalonie  Aeid. — ^When  this  acid  is  heated  in  a 
fractionating  flask,  decomposition  soon  sets  in  with  evolution  of  carbon 
dioxide,  and  the  residue,  after  repeatedly  fractionating  under  reduced 
pressure, yields  a  liquid  which  boils,  apparently  constantly,  at  157 — 161^ 
(15  mm.),  and  which  was  at  first  thought  to  be  acetalacetic  acid 
(CjH40)2CH-OH2-OH3-OOOH.  The  analyses,  however,  show  that  this 
substance  consists,  for  the  most  part,  of  aldehydopropionic  acid 
(p.  16),  elimination  of  alcohol  having  taken  place  during  the  distilla- 
tion owing,  probably,  to  the  unavoidable  presence  of  small  quantities 
of  water. 

0-2658  gave  0-4740  00,  and  01607  H^O.     0  =  4863  ;  H  =  671. 
0-2514     „    0-4372  OO2    „   01437  HjQ.     0  =  4853;  H  =  6-39. 
OOOH-OHj-OHg-OHO  requires  0  =  47  05  ;  H-5'88  per  cent. 
OOOH*CHj*OH2'OH(002H5)2  requires  0  =  54-54 ;  H  =  909  per  cent. 

In  order  to  confirm  this  view,  the  liquid  was  heated  with  an  equal 
quantity  of  phenylhydrazine  for  10  minutes  at  150°  and  poured  into 
ether,  when,  on  standing,  a  white,  crystalline  substance  separated, 
which,  after  crystallisation  from  acetic  acid,  melted  at  19P  and  gave 
the  following  results  on  analysis. 

0^)601  gave  01502  00,  and  0-0350  HjO.     0  »  681 7  ;  H  =  6-47. 
0-1258  gave  21-3  c.c.  nitrogen  at  19"^  and  768  mm.     N  =  19-42. 
CjeH^gN^O  requires  0  =  6809  ;   H  =  638  ;  N  =  1985  per  cent. 

This  substance^  on  examination,  was  found  to  be  identical  with  the 
condensation  product  formed  by  heating  aldehydopropionic  acid  with 

*  The  four  analyns  given  here  were  carried  out  with  four  di£ferent  prepanitioDS 
of  the  add. 


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16     FEB  KIN  AHD  SPRANKLING :  /8-ALDEHYDOPBOPIONIC  ACID 

phenjlhjdi'azine  (see  below),  and  thus  it  is  probable  that  this  aldehydo- 
acid  was  present  in  the  oil  obtained  by  the  distillation  of  acetalmalonic 
acid. 

fi'Aldehydopropumie  acid,  CHO-CHj-CHj-COOBL 

In  order  to  prepare  this  substance,  acetalmalonic  acid  is  heated  with 
about  four  times  its  weight  of  water  at  180 — 190°  for  4  hoursi  the 
solution  evaporated  on  the  water-bath,  and  the  residue  allowed  to  stand 
over  sulphuric  acid  in  a  well  exhausted  desiccator  for  4  or  5  days. 

The  yellow,  oily  residue  thus  obtained,  on  analysis,  gave  numbers 
agreeing  approximately  with  thosev  required  for  j^ldehydopropionio 
acid.* 

I.  0-2084  gave  0-3611  CX)g and  01127  HjO.  0  =  47-40;  H-6-01. 
U.  0-2124     „    0-3675  CO,    „    01132  HjO.  0«  47-20 ;  H= 5-92. 

III.  0-1703      ,,0-2928  00,    „    0-0890 H^O.  0« 46-89  ;  H  =  582. 

IV.  01379      „  0-2300 OOj    „    00806 H^O.  0  =  45-47;  H  =  647. 
V.  01576      „   0-2649  00,    „    00909 H,0.  0  =  45-90;  H  =  6-40. 

OHO'OHg'OHj'OOOH  requires  0  =  4705 ;  H  =  5-88  per  cent. 

P-Aldshydopropionie  cusid  is  a  slightly  brownish  liquid  which  dissolves 
readily  in  water,  freshly  prepared,  its  solution  reduces  Fehling's  solution, 
and  produces  a  pink  colour  when  mixed  with  a  solution  of  rosaniline 
hydrochloride  which  has  been  decolorised  with  sulphur  dioxide.  When 
heated  at  150°  with  phenylhydrazine  for  10  minutes,  condensation 
readily  takes  place,  and  if  the  product  is  poured  into  ether  a  white, 
crystalline  substance  separates  on  standing,  which,  after  recrystallisa- 
tion  from  acetic  acid,  gave  the  following  results  on  analysis. 

00590  gave  101  c.c.  nitrogen  at  18°  and  758  mm.     N*. 20'00. 

This  substance,  of  which  a  fall  analysis  is  given  on  p.  15,  melts  at 
192°  and  is  evidently  the  phenylhydrazide  of  the  phenylhydrazone  of 
aldehydopropionic  acid,  O^Hg-NH^NIOH-OHj-OHj-OO-NH-NH-OeHg, 
which  contains  19-85  per  cent,  of  nitrogen. 

Oxidation  of  Aldehydopropionic  Acid,    FomiaUon  qf  Succinic  Acid. 

When  aldehydopropionic  acid  is  left  exposed  to  the  air,  it  darkens  in 
colour  and  gradually  deposits  crystals,  ultimately  being  converted  into 
a  brown,  pasty  mass,  which  in  contact  with  porous  porcelain  slowly 

*  As  this  substance  would  not  crystallise,  analyses  of  each  preparation  were 
made,  and  some  of  these  varied  as  much  as  8  per  cent  from  the  theoretical ;  we 
therefore  wish  it  to  be  distinctly  understood  that  we  do  not  consider  that  the 
aldehydo-acid  made  in  this  way  is  pore.  All  the  preparations  contained  a  small 
amount  of  ash  derived  from  the  tube  in  which  they  were  prepared  ;  this  was  allowed 
for  in  the  analyses. 


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AND  /S-ALDIHTDOISOBUTTBIC  ACID.  17 

beeomes  a  nearly  oolourleBs,  crystalline  mass,  the  sticky,  oily  impurity 
being  only  very  gradually  absorbed. 

The  crystals  were  purified  by  reorystallisation  from  hydrochloric 
add  with  the  aid  of  animal  charcoal,  and  in  this  way  colourless  plates 

were  obtained  which  melted  at  18P  and  had  all  the  properties  of 

Boecinic  add.     Analysis. 

01201  gave  01786  00^  and  00561  H^O.     0  =i 4056 ;  H  =  518. 
00OH*Cn,*CHs-C0OH  requires  0^40*68;  H»508  per  cent. 

This  experiment  shows  that  aldehydopropionio  acid  is  slowly 
converted  into  succinic  acid  by  the  oxygen  of  the  air,  and  this  change 
takes  i^aoe  very  rapidly  when  oxidising  agents  are  employed.  A  small 
quantity  of  the  aldehydo-acid,  after  being  heated  to  boiling  with  dilute 
nxferieadd  (20  per  cent.)  for  some  hours  until  no  further  oxidation  took 
place,  was  evaporated  repeatedly  on  the  water-bath  with  the  addition  of 
small  quantities  of  water,  until  a  colourless,  crystalline  residue  was 
left.  This,  after  recrystallisation  from  hydrochloric  add,  melted  at 
181 — 184°  and  consisted  of  succinic  acid. 

0^598  gave  0-0898  OOj  and  0-0279  HgO.     C  =  4096 ;  H  =  518. 
OOOH-GHj-CHs'COOH  requires C » 40-68 ;  H » 508  per  cent. 


Adtcdion  rf  Aldekifdapropunne  Acid.     Formaiion  of  BuiyrolcustanSf 
CHj-  OH,-  CH, 

Flye  grams  of  the  pure  aldehydo-acid  were  dissolved  in 
water  and  treated  with  three  times  the  calculated  quantity  of  4  per 
eent  aodiom  amalgam,  carbon  dioxide  being  passed  through  the  liquid 
ukl  the  temperature  kept  below  10^  during  the  whole  operation,  in 
order  to  avoid,  as  far  as  possible,  risk  of  polymerisation  or  condensa- 
tion ;  after  separating  the  mercury,  the  solution  was  made  strongly 
Mad  with  sulphuric  acid,  heated  to  boiling  for  half  an  hour  in  a  reflux 
i^iparstos,  and  then  repeatedly  extracted  with  ether.  The  ethereal 
solution,  when  dried  and  evaporated,  deposited  a  colourless  oil,  which, 
after  twice  fractionating,  boiled  at  203—208°.  On  analysis,  it  gave 
niunbers  agreeing  with  those  of  butyrolactone,  which,  according  to 
Fittig  and  Boeder  {Annalen,  QSfJ.  1886,  22),  boils  at  206"^. 

0 1366  gave  0-2760  CO,  and  00888  H,0.     C  =  55-51 ;  H  «  727. 
C^HjO,  requires  0-55-81 ;  H«6-97  per  cent. 


VOU  LXXV. 

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18     FERKIN  AND  8PRANKLING :  /S-ALBBHTDOPROPIONIC  ACID 


Action  of  Ccmatic  Soda  on  P-Aldehydopropionie  Add,     Syntftens  of 
'  TorBphthalie  Aeid. 

This  synthesisi  which  is  ezplained  in  the  introduction  to  this  paper, 
was  carried  out  as  follows.  /3-Aldehydopropionic  acid  (10  grams) 
was  dissolved  in  an  excess  of  dilute  sodium  hydroxide  and  the  solution 
evaporated  in  a  flat  glass  basin  nearly  to  dryness,  water  was  then 
added  and  the  solution  again  evaporated^  this  operation  being  con- 
tinued during  three  days ;  the  concentrated  liquid,  after  being  acidified 
and  allowed  to  stand  over-night,  deposited  a  small  quantity  of  a 
brownish  powder,  which,  on  examination,  was  found  to  be  crude  tere- 
phthalic  acid.  This  was  purified  by  dissolving  it  in  dilute  sodium 
carbonate,  boiling  with  animal  charcoal  until  most  of  the  colour  had 
been  removed,  and  then  treating  the  solution  at  0°  with  permanganate 
until  the  violet  colour  remained  permanent  for  2  minutes ;  the  filtrate 
from  the  manganese  precipitate  was  coDcentrated,  and,  while  still  hot, 
acidified  with  hydrochloric  acid ;  the  colourless,  crystalline  precipitate, 
which  separated  rapidly,  had  all  the  properties  of  terephthalic  acid. 
It  was  almost  insoluble  in  water  and  ether,  did  not  melt  at  270%  and 
on  heating  in  a  small  test  tube  it  sublimed  apparently  without  melting. 

The  small  quantity  of  acid  remaining  (about  0*2  gram)  was  converted 
into  its  methylic  salt  by  Baeyer's  {Annalen,  1888,  245,  140)  method  by 
heating  with  phosphorus  pentachloride,  mixing  the  product  with 
methylic  alcohol,  and  purifying  the  crystals  which  separated,  by  re- 
crystallisation  from  methylic  alcohol,  with  the  aid  of  animal  charcoal ; 
the  colourless  plates  thus  obtained  were  very  sparingly  soluble  in 
methylic  alcohol  and  melted  sharply  at  140%  the  melting  point  of 
the  methylic  salt  of  terephthalic  acid.  A  specimen  of  the  methylic  salt 
prepared  from  pure  terephthalic  acid  was  found  to  be  identical  with 
the  synthetical  substance  in  every  respect,  moreover,  an  intimate 
mixture  of  the  two  preparations  melted  sharply  at  140^.  These  experi- 
ments prove  conclusively  that  the  acid  formed  by  the  action  of  sodium 
hydroxide  on  /3-aldehydopropionic  acid  is  terephthalic  acid,  and  it  is  un- 
'  fortunate  that,  in  spite  of  a  number  of  experiments,  we  have  been 
unable  to  devise  a  better  method  for  the  condensation  of  the  aldehyde, 
as  the  yield  of  terephthalic  acid  obtained  was  certainly  not  more  than 
5  per  cent. 


P-AldekydoUobutfjric  Acid,  CHO*OH2*OH(OH8)-OOOH. 

The  first  step  in  synthesising  this  substance  was  to  prepare  ethylie 
acetalmethylmalonate,  and  this  was  readily  accomplished  by  heating 
the  sodium  derivative  of    ethylie  methylim^ionate  with  bromacetal 


Digitized  by  VjOOQIC 


AND  /d-ALDBHTDOISOfiUTrBIC  AOIl>.  19 

ttuder  the  conditions  already  described  in  the  case  of  ethylic  acetal- 
malonate.  The  ethjlio  malonate  employed  in  these  experiments 
was  made  by  the  etherification  of  pure  methylmalonic  add;  the 
quantities  of  the  sabstanoes  nsed  in  the  synthesis  of  ethylic  acetal- 
methylmalonate  were, 

Ifthylic  methylmalonate        54  grams. 

Sodinm.... 7*2      ,^ 

Bromaoetal * 40      „ 

After  isolating  the  product  in  the  way  described  in  the  case  of  ethylic 
aoetalmalonatey  the  crude  oil  was  submitted  to  careful  fractionation 
and  the  fraction  166^(26  mm.),  which  consisted  of  nearly  pure  ethylic 
aoetalmethylmalonate,  was  analysed  with  the  following  result. 

0-1491  gave  0*3056  00,  and  01204  H^O.    O«67'20;  H-8-97. 
{0AO)jCH-CHj-CH(OHsXCOOC^5)2  requires  0-57-92;  H- 8-96  per  cent. 

AcetalmMsfhMhnie  Aeid,  (0^oOVOH-GH2-OH(OHs)(OOOH),. 

This  acid,  which  was  prepared  by  the  careful  hydrolysis  of  its 
ethereal  salt,  is  a  colourless  syrup  readily  soluble  in  water. 

01965  gave  0-3624  00,  and  01404  H,0.    0  «  50*30  ;  H  »  7*94. 
Oi^igO^  requires  0  «  51  -28 ;  H  =  769  per  cent. 

The  tilver  aaUf  prepared  by  precipitating  a  neutral  solution  of  the 
ammonium  salt  with  silirer  nitrate,  is  a  white,  amorphous  powder, 
which  readily  darkens  when  exposed  to  light. 

0-2026  gave,  on  ignition,  0*0980  Ag.    Ag  »  48*37. 

O^oH^^AgjO^  requires  Age 48*19  per  cent. 

Aldehydoisobutyrie  add,  obtained  by  heating  acetalmethylmalonic 
add  witii  water  at  180^  for  4  hours,  and  evaporating  the  liquid  on  a 
water  bath,  is  an  oil  which,  after  standing  for  some  days  over  sul- 
phuric acid  in  a  vacuum,  was  analysed  with  the  following  results.* 

0-1933  gave  03653  00,  and  01238  H,0.    0 «: 51-53 ;  H ^ 7*28. 
CHO-OH,-OH(0H,)-0OOH  requires  0-51*72 ;  H-6-89  per  cent. 

This  Bubstanoe  is  very  similar  to  aldehydopropionio  add  in  its  pro- 
perties, and  its  constitution  is  proved  by  the  fact  that,  when  oxidised 
with  nitric  acid,  it  yidds  fnUh/^fhtteoifHe  add  ;  this,  after  recrystallisa- 
tion,  melted  at  110 — 112°,  and  gave  the  correct  numbers  on  analysis. 

0*2142  gave  0*3558  00,  and  01288  H,0.    0  =  45-30 ;  H  -  6-40. 
C00H-OH(OH3)-OH,'0OpH  requires  0-45*46;  H-606  per  cent. 

OWSHS  COLLXOX, 

Mavohxstkb. 

«..  I    ■  ■     '■      ■      ■  i  «  I  I  Ml  ■   I     ii  »ii  I  ■  «t»m ■,. I  I      .    II  ■  m 

*  See  footnote,  ik  16. 

Digitized^ySoOgle 


20     WOOD,  SPIVET,  AND  BASTE RFIELD :  CANNABINOL.      PART  I. 


III. — CannahinoL     Part  I. 

By  Thomas  Barlow  Wood,  M.A. ;  W.  T.  Nkwton  Spivet,  M.A. ; 
Thomab  Hill  EAiSTBRriSLD,  M.A.,  Pb.D. 

In  a  paper  oommunicatecl  to  the  Society  in  1896  (Trans.,  1896,  69, 
539)  the  authors,  under  the  name  of  '<  cannabinol,"  described  a 
physiologically  active  substance  which  they  had  isolated  from 
**  diaras/'  the  exuded  resin  of  Indian  hemp.  From  the  constancy  of 
composition  of  a  number  of  preparations  of  this  substance  obtained 
from  different  samples  of  '*  charas/'  it  was  believed  to  be  a  definite 
chemical  compound  of  the  formula  C^^B^fi^  i  ^^  conclusion  seemed 
to  be  justified  by  the  determination  of  the  molecular  weight,  and  by 
the  examination  of  several  derivatives.  Since  then,  the  authors  have 
further  examined  cannabinol,  and  have  found  that  it  is  a  mixture  of 
at  least  two  compounds  having  similar  physical  characters.  One  of 
these,  of  the  formula  C^^^O^  has  been  isolated,  and  it  is  proposed  to 
retain  the  name  cannabinol  for  this  compound. 

During  the  progress  of  this  investigation,  a  note  on  oxycannabin  by 
Messrs.  Dunstan  and  Henry  appeared  in  the  Proceedings  of  the  Society 
(Proc.,  1898,  p.  44),  in  which  the  formula  O10H10NO4  and  CjgH^OAc 
were  assigned  to  oxycannabin  and  acetylcannabinol  respectively. 
FroBi  the  description  of  these  substances,  there  can  be  no  doubt  that 
they  are  identical  with  those  we  have  obtained,  but  the  reeultfl 
of  our  analyses  correspond  with  the  formulas  C^jH^iNO^  for  oxy- 
cannabin and  O^^^fi^'^i^fi  ^^^  acetylcannabinol.  These  formula 
are  confirmed  by  molecular  weight  determinations,  and  by  analyses  of 
many  derivatives.  Dunstan  and  Henry  {loe.  eit.)  state  that,  on 
oxidising  cannabinol  with  nitric  acid,  normal  butyric  acid  is  formed ; 
we  can  confirm  this  statement,  with  the  addition  that  larger  quanti- 
ties of  normal  valeric  and  caproic  acids  are  produced  at  *the  same  time. 

As  the  present  paper  deals  mainly  with  the  substances  produced 
by  the  breaking  down  of  the  cannabinol  molecule,  the  authors  have 
only  described  such  of  its  reactions  as  suffice  to  show  that  it  is  a  true 
ishemioal  compound.  An  account  of  the  reactions  of  cannabinol, 
together  with  a  more  complete  examination  of  several  of  the  com- 
pounds described  below,  will  shortly  be  brought  before  the  Society. 

When  crude  cannabinol  (the  red  oil  obtained  by  fractionating 
alcoholic  charas  extract  under  diminished  pressure)  is  treated  with 
nitric  acid  under  certain  conditions,  it  yields  a  yellow,  crystalline 
substance,  the  analysis  of  which  corresponds  with  the  formula 
C^jHigN^jOs  (Proc.,  1898,  p.  66),  but  determinations  of  the  molecular 
weight  show  that  a  higher  formula  is  required.     As  it  has  aoidio 

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WOOD,  SPIVBT,   AND  SA8TERFIBLD :  CANNABINOL.      PART  I.      21 

propratieBy  Baits  were  inrepared  and  analysed,  and  their  composition 
proTes  that  the  formula  is  C^{H^fig^  which  agrees  with  the  molecular 
weight  determinations.  It  is  readily  reduced  by  boiling  with 
hydriodio  aoid  and  phosphorus,  yielding  the  hydriodide  of  a  base ; 
the  latter  has  not  as  yet  been  isolated,  owing  to  the  readiness  with 
which  it  oxidises.  As  the  formula  Cg^H^gNgOg  represents  the  trinitro- 
deriyatiye  of  a  compound,  G^^^fiv  the  presence  of  the  latter  in  crude 
cannabinol  is  (urobable,  and  this  is  definitely  proved  by  the  isolation 
of  the  acetyl  derivative,  C^B.^O^^CJS^Oy  from  a  crude  cannabinol. 

After  the  separation  of  the  'crystalline  acetyl  derivative  from  the 
products  obtained  by  the  acetylation  of  crude  cannabinol,  an  oily 
residue  was  left  amounting  to  more  than  three-quarters  of  the  acetyla- 
tion product,  and  from  it  by  treatment  with  acetic  anhydride,  no 
other  crystaUine  acetyl  derivative  could  be  obtained ;  it  appears  to 
oontain  Uie  acetyl  derivatives  of  one  or  more  substances  with  a  lower 
percentage  of  carbon  than  GgiHggOj. 

"  Crude  cannabinol "  is,  therefore,  a  mixture  of  cannabinol,  CjiH^Ogy 
with  one  or  more  compounds  probably  of  lower  molecular  weight. 

The  fact  that  cannabinol  forms  an  acetyl  derivative  proves  that  it 
contains  a  hydrozylic  group,  and  the  failure  of  all  attempts  to 
obtain  an  ethereal  salt  from  the  trinitro-compound  referred  to  above, 
makes  it  probable  that  the  acidity  of  the  latter  is  not  due  to  the 
presence  of  a  carbozyl  group^  but  to  the  influence  of  the  nitro-groupe  on 
the  hydroxyl  group. 

On  oxidising  the  trinitro-derivative  by  boiling  it  for  several  hours 
with  fuming  nitric  acid,  and  pouring  the  product  into  water,  a  yellow, 
flooculent  precipitate  was  deposited ;  this  was  filtered  ofC,  and  the 
add  filtrate  steam  distilled ;  the  distillate  was  found  to  contain  normal 
butyric,  valeric,  and  caproic  adds.  The  normal  butyric  acid  was 
identified  by  its  ealdum  salt,  the  normal  valeric  and  caproic  adds  by 
their  anilides.  By  direct  oxidation  of  crude  cannabinol  with 
nitric  add,  the  same  fatty  adds  were  obtained,  and  caproic  acid 
was  aieo  obtained  when  potassium  permanganate  or  chromic  acid 
mixture  was  employed. 

The  yellow,  flocculent  precipitate,  on  crystallisation,  gave  a  mixture 
of  oily  adds  containing  nitrogen,  and  a  pale  yellow,  crystalline  com- 
pound, the  oxycannabin  of  Bolas  and  Frauds  (Chem,  News^  1871,  24, 
77) ;  to  this  they  gave  the  formula  O^fl^^ji^jt  l>ut  the  results  of 
their  analyses  agree  equally  well  with  the  authors'  formula  G^jHi^NO^. 
Dunstan  and  Henry,  in  their  note  (Froc.,  loc.  cit.),  state  that  oxy- 
cannabin "  does  not  dissolve  in  aqueous  alkalis  unless  warmed  with 
them  in  a  closed  tube.  By  addifying  the  resulting  solution,  an  acid 
is  predpttated  which  is  at  present  under  investigation.  Oxycannabin 
would,  therefore,  appear  to  be  a  lactone."    The  present  authors  find, 

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22     WOOD,  SPIVKT,  AND  SASTBBFIISLD :  OANNABINOL.     PART  I. 

however^  that  ozyoannabin  disBolves  in  aqueous  oanstic  soda  if  boiled 
iHth  it  for  a  few  minutes,  and  that  unaltered  ozyoannabin  is  preeipi- 
tilted  on  addifioation.  They  have  proved  it  to  be  a  lactone  by  the 
preparation  and  analysis  of  salts  of  the  corresponding  ozy-aoid,  but 
this  ozy«acid  has  not  been  isolated,  since  it  is  at  once  re-converted 
into  the  lactone  when  set  free  from  its  salts.  In  fact,  its  tendency 
to  undergo  this  change  is  so  great  that,  on  treating  the  silver  salt 
With  ethylio  iodide,  the  lactone  is  obtained  instead  of  the  ethylie 
salt. 

On  oxidation  with  dilute  nitric  add  at  186°,  ozyoannabin  yields  a 
sparingly  soluble  nitro-lactonic  acid  of  the  formula  GjQHgNO^'OOOH 
together  with  a  very  soluble  tribasic  acid,  C^H^NOg. 

On  reduction,  ozyoannabin  yields  a  compound,  Oi^H^gNO^t  which 
corresponds  to  the  reduction  of  a  nitro-group  in  ozyoannabin  to  an 
amido-group.  On  this  evidence,  the  authors  propose  for  ozycannabin 
the  name  nitrocannabino-lactone,  and  for  the  reduction  product  the 
name  amidocannabino-lactone. 

The  amido-kctone  is  readily  diazotised,  and  an  attempt  was  made 
t6  prepare  cannabino-lactone  directly  from  it  by  Friedlander's  method, 
but  it  was  found  more  convenient  to  prepare  iodocannabino-lactone, 
OjjHjjIO],  by  adding  potassium  iodide  to  the  diazotised  solution,  and  to 
riiduce  this  with  sodium  amalgam  in  alkaline  solution.  The  oily  canna- 
Mno-lactone,  Oj^HijOg,  thus  obtained,  was  converted  into  colourless 
crystalline,  cannabino-lactonic  acid,  Gj^H^oO^,  by  boiling  it  with  an 
alkaline  solution  of  potassium  permanganate ;  this  action  corresponds 
to  the  oxidation  of  a  methyl  group  to  a  carbozyl  group.  On  reduction 
With  hydriodic  add  and  phosphorus,  the  lactonic  acid  yields  a  dibasic 
Add  of  the  formula  O^jH^^O^  thus  affording  confirmation  of  its  lactonio 
tinture. 

From  the  fact  that  a  methyl  group,  both  in  cannabino-lactone 
ted  in  its  nitro-derivative,  is  ozidised  to  a  carbozyl  group,  and  from 
(he  behaviour  of  nitrocannabino-lactone  on  reduction,  and  subsequent 
diazotisation,  the  presence  of  a  benzene  nucleus  in  cannabino-lactone  is 
probable.  In  order  to  confirm  this,  and,  further,  to  ascertain  the 
Mructure  of  the  lactone  ring,  the  lactonic  acid  was  fused  with  caustio 
tK>ta8h ;  in  this  way,  isophthalic  add  was  obtained,  and  identified  by 
conversion  into  its  methylic  salt.  However,  when  cannabino-lactone 
Was  fused  with  potash,  metatoluic  acid  was  formed,  together  with  iso- 
phthalic acid.  The  formation  of  these  two  adds  definitdy  proves 
the  presence  in  cannabino-lactone  of  a  benzene  nucleus,  with  two 
Aide  chains  in  the  meta-position  relatively  to  each  other,  one  of 
these  chains  bdng  a  methyl  group.  The  second  side  chain  must 
evidently  contain  the  lactone  ring,  and  on  the  assumption  that  it  is  a 
y-lactone,  which  from  its  great  stability  is  probable,  there  appear  to 

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WOOD,  SPIYET,  AMB  SASTKBnKLD:  CAKNJLBINOL.     PABT  I.     23 

be  mily  three  possible  formula,  namelj,  those  of  the  thiee  metatolyl- 
bntyroiaictoiiei^ 

CH,-9,H,  CH,-9,H,  CH,-9,H, 

L  CH-CHj-CHj      II.  CHj-CH-CHj,      HI.  CHj-CHj-CH 

Synthesee  of  these  three  lactones  are  at  present  in  progress,  with  a 
view  to  deciding  which  of  them  is  identical  with  cannabino-Iactone. 

The  following  table  shows  the  relationships  of  the  -oompoands 
described  in  this  paper. 

Gannabinol,  O^^H^O,. 
Aoetylcamiabinol,  C^HgjOj-CXJCH,. 
Trinitrocannabinol,  0„Hj3fe^O,)8' Og. 

Oannabino-lactone,  (l)CH3-CgH^<^^[»>CO(3). 

Nitrocannabino-lactone(oxjrcannabin),  (1)  ^0>C^U^<S^^i^><X) 

Amidocannabino-lactone,  (1)  ^«>CeH3<^^i>C0  (3). 

lodocannabino-lactone,  (1)  ^^p>C^M^<S!^^i^>00  (8). 

Oannabino-hictonio  acid,  (1)  COOH- C3H^<^i>00  (3). 

Nitrocannabino-lactonic  acid,  (1)  ^Q>CJ^^<S^i>00  (3). 
Carbozyphenylbatjric  add,  OOOH-OgH^^CjH^-OOOH  (3). 

EXPSBIMSNTAL. 

Triniiroeannabinols  ^/^^^{ISO^fiy — This  compound  is  produced  on 
adding  fuming  nitric  acid  (5  cc),  drop  by  drop,  to  a  well  cooled  solu- 
tion of  crude  cannabinol  (8  grams),  dissolved  in  glacial  acetic  acid 
(18  cc),  the  temperature  being  kept  down  by  immersing  the  flask  in 
ioeeold  water.  After  standing  for  several  days,  the  crystals  are  col- 
leeted;  the  yield  is  20  per  cent.  (1*6  grams)  of  the  crude  cannabinol 
used.  The  compound  is  easily  soluble  in  benzene,  phenol,  alcohol^  and 
ether  ;  it  is  also  readily  soluble  in  hot,  but  only  sparingly  in  cold,  glacial 
acetic  acid,  which  is  the  most  convenient  solvent  for  its  recrystallisa- 
tion.  It  crystallises  in  bright  yellow  plates,  which,  when  quickly  heated, 
melt  at  160^  (uncorr.)  with  some  decomposition. 

Four  preparations  were  analysed 

A  and  B,  purified  through  the  ammonium  salt.  C.  Five  times  re- 
crystallised  from  glacial  acetic  acid,  D.  Sample  0,  once  recrystallised 
from  alcohol. 

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24     WOOD,  SPIVBY^.ANO  EASTEBFIJSLD :   GANKABINOL.     PABT  I. 

^  f  0-1417  gave  02935  C»,  and  00678  H,0. 

'  1 0*1235    „     10  CO.  moist  nitrogen  at  18^  and  760  mm. 
B.    0- 

lo- 


B.    01676  „  0-3480  00,  and  0-0835  HjjO. 

•1860  „  0-3855  00,    „    00913  H,0, 

1-1440  f,  11-5  C.C.  moist  nitrogen  at  21^  and  756  mm. 

D.     0-1527  „  0-3180  00,  and  0-0750  H,0. 


Calculated  for  Foand. 

CnH,|N,Oa.  A.  B.     '          a  D. 

0-56-6  percent 56*5  566        565  56-8 

H«    5-2      „         5-3  5-5          54  55 

N=    9-4      „         9-3  —           90  — 

The  molecnlar  weight  was  determined  by  the  freezing  point  method 
in  benzene  and  in  phenol. 

In  benzene  (i)  0*5220  gram,  dissolved  in  20  grams  of  benzene^  lowered 
the  freezing  point  by  0-312"^. 

(ii)  0*9513  gram,  dissolved  in  20  grams  benzene,  lowered  the  freezing 
point  by  0-570°. 

In  phejiol  (iii)  0*4733  gram,  dissolved  in  20  grams  phenol,  lowered 
the  freezing  point  by  0-410°. 

(iv)  1-0023  grams,  dissolved  in[20  grams  phenol,  lowered  the  freezing 
point  by  0-900° 

Calcalated  for  Found. 

CiH„N,Os.  (i).  (u).  (iii).  (iv). 

Molecular  weight -445 409        409        427        412 

Satae. — ^The  compound  has  acidic  properties,  forming  salts  of  potas- 
sium, sodium,  ammonium,  and  silver,  all  of  which  are  bright  yellow, 
crystalline  compounds  sparingly  soluble  in  water,  easily  in  alcohol.  They 
are  best  crystallised  by  diluting  their  hot  alcoholic  solutions  with  water. 
The  potassium  and  sodium  salts  are  explosive,  the  silver  salt  is  not 

Sodium  Salt. — The  most  soluble  of  all  the  salts  examined,  the 
saturated  solution  at  15°  containing  1  part  of  salt  in  120  parts  of 
solution.  It  is  prepared  by  dissolving  the  acid  in  excess  of  alcoholic 
soda  solution  and  diluting  with  water.    Two  samples  were  analysed* 

0*2130, at  160°,  lost  00290  H^O and  gave  0-0265  Na,S04.   Na» 3*9 ; 

H,0«13-6. 
0-1545  gave  00205  Na,S04.   Na=4-3. 

NaO^jH^^NsOg  +  4H2O  requires  Na  -  4*3 ;  H^  - 13*4  per  cent 

Fotaeeium  salt,  prepared  in  the  same  way  as  the  sodium   salt, 
equires  for  solution  2000  parts  of  water  at  15°,  and  500  at  100°. 

.  0*1210  lost  no  weight  at  150°,  and  gave  0*0220  K^^.    E»8-2. 
0-1300  gave  0-230  E^SO^;  K-7-9. 

KOjiH^^gOg  requires  K»8*l  per  cent. 

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WOOB,  8PIV1ST,  AND  EASTEBFIELD :  CANNABINOL.     FABT  I.      25 

Ammonium  tali  may  be  prepared  by  dissolving  the  aoid  in  boiling 
ammonia  solution,  when  the  salt  crystfdlisee  out  on  cooling,  or  by  dis- 
solving the  acid  in  excess  of  alcoholic  ammonia  and  diluting  with 
water.  It  requires  for  solution  1600  parts  of  water  at  15%  and  200 
at  100°. 

01170  gave  0-2330  OOj  and  00605  H^O.    0  =  543  ;  H  =  6-7. 
0-1312    ,,  13*3  C.C.  moist  nitrogen  at  IS''  and  758  mm.    N»  11*7. 
0-4190    „  on  distillation  with  sodajNHg  =  9-7c.c.N/10  HCL  NHg  =  3*9. 
01320    „  0-2640  00,  and  00690  H^O.    0  =  54-5 ;  H  =  5-8. 
0-1695     „  170  C.C.  moist  nitrogen  at  19°  and  750  mm.    N  =  121. 
NH4-OaH2jN808require80«54-5;H=:5-6;N  =  121  ;NH,  =  3-7  per  cent. 

Sther  9aU,  prepared  either  by  adding  silver  nitrate  solution  to  the 
Bolntion  of  the  sodium  salt,  or  by  boiling  the  alcoholic  solution  of  the 
add  with  excess  of  silver  carbonate.  A.  Was  prepared  from  the  sodium 
salt  and  recrystallised  from  alcohoL  B.  From  the  acid  and  silver 
carbonate.     0  is  B  recrystallised. 

(0-1900  gave  0-3180  OOg,  00715  Hfi,  and  00362  Ag.    0»45-6; 
A.-J         H  =  4-2;Ag=191. 

V  0*1829  gave  11-2  c.c.  moist  nitrogen  at  16°  and  766  mm.   N  »  7*2. 

B.  01580    „    0-2673  OOj,  0-0586  HjO  and  00295  Ag.    0  =  461; 

H=41;Ag  =  18-8. 
(0-1850  gave 0-3090  CO2,  0-0675  Kfi    „    00357  Ag.    0-45-5; 

C.  <  H  =  41;Ag  =  19-3. 

'  0-2600  gave  16*2  c.c.  moist  nitrogen  at  18° and  758  mm.    N  =  7'2. 
AgCjjHjjNjOg  requires  0  =  45-6 ;  H  =  4*0;  N  =  76;  Ag  =  194  per  cent. 

BaducUon  i^f  TrifUH'ocaMnalnnol, — ^Trinitrocannabinol  is  reduced  by 
bailing  with  hydriodic  aeid  and  phosphorus  in  acetic  acid  solution ; 
3;7  grams  of  trinitrooannabinol  were  dissolved  in  50  c.c.  of  glacial 
acetic  add^  and  boiled  for  Ij^  hours  with  25  c.c.  of  hydriodic  acid 
spu  gr.  1*69  and  4  grams  of  yellow  phosphorus;  the  almost  colourless 
solution  was  then  filtered  from  the  excess  of  phosphorus,  and  distilled 
down  to  one-third  its  volume.  The  pale  yellow  crystals  of  hydriodide 
which  were  deposited  on  cooling  were  collected,  washed  with  acetic 
add,  and  dried  in  a  vacuum  over  solid  potash. 

Attempts  to  isolate  the  base  failed,  as  when  set  free  from  the 
hydriodide  it  is  at  once  oxidised,  with  fprmation  of  coloured  products. 

The  hydriodide  was  analysed,  and  gave  the  following  numbers, 
0=41-2;  H=5-2;  1=413;  N  =  50  per  cent. 

The  authors  do  not  feel  justified  in  making  any  statement  as  to  the 
constitution  of  the  product  of  reduction  until  they  have  isolated  the 
base  and  made  a  further  examination. 

Aceiylcannabinol^  O^H^gO^-OO-OHg.— Orude  cannabinol  is  readily 

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26      WOOD,  SPIVEY,  AND  EASTERFIELD :  CANNABINOL.      PART  V 

aoetylated  by  boiling  it  with  aoetic  anhydride  or  with  acetic  chloride. 
After  distilling  off  the  excess  of  acetic  anhydride  and  rectifying  the 
residue  under  diminished  pressure,  an  oil,  lighter  in  colour  and  more 
mobile  than  the  original  crude  cannabinol,  is  obtained;  this  some- 
times, on  stfinding,  but,  better,  by  dissolving  it  in  alcohol  and  cooling 
the  solution  to  0^,  deposits  a  white,  crystalline  substance,  which  can  be 
purified  by  crystallisation  from  alcohol,  light  petroleum,  or  acetic  acid ; 
it  melts  at  75^,  and  is  evidently  identical  with  the  *  aoetylcannabinol, 
OjgH^gOAc,'  mentioned  by  Dunstan  and  Henry  {loc.  eU,y 

Analysis  indicated  as  the  simplest  formula  OjgHjgO^  (Proc.,  1898, 
66),  but  determination  of  the  molecular  weight  and  the  results  of 
saponification  show  that  the  higher  formula,  C^sH^gOg,  must  be  adopted 
(IVoc.,  1898,  163). 

The  following  samples  were  analysed.  A.  Recrystallised  from 
alcohol.  B.  Four  times  recrystallised  from  alcohol.  0.  Becrystal- 
lised  from  light  petroleum  and  then  from  acetic  acid. 

•1637  gave  04420  00^  and  01101  H^O.     C  =  78-4  ;  H= 79. 
•1118     „    0-3208  OOj    „    00820  HjO.     C-78-3 ;  H  =  8-l. 
^  f  01250    „    0-3695  COj    „    00914  HjO.    C  =  78-4;  H  =  81. 
10-1290    „    0-3692  CO2    „    00928  HjO.    0-781 ;  H- 8-0. 
0.     01860    „    0-6315  COg    „    0-1330  HgO.    0-77-9 ;  H- 8-0. 
^16^18^2  requires  0  =  78-3 ;  H  =  7'8  per  cent. 
^21^25^2* OO-OHj  requires  0  =  78-4  ;  H2O  =  80  per  cent. 
O^gH^gOAc  (Dunstan  and  Henry)  requires  0  =  80-6  ;  H=8*7  per  cent. 

The  molecular  weight  was  determined  by  the  freezing  point  method, 
in  glacial  acetic  acid  and  in  benzene. 

In  gkbciai  ctcetie  cteid, — (i)  0*2043  gram,  dissolved  in  20  grams  of 
glacial  acetic  acid,  caused  a  depression  of  0*123°. 

(ii)  0-6052  gram,  dissolved  in  20  grams  of  glacial  acetic  acid,  caused 
a  depression  of  0*310°. 

In  60fi«0ne.*— (ili)  0*1877  gram,  dissolved  in  17*04  grams  of  benzene, 
caused  a  depression  of  0*140°. 

(iv)  0-3032  gram,  dissolved  in  17*04  grams  of  benzene,  caused  a 
depression  of  0*240°. 


fOl 
1 0-1 


Calculated  for 

Calcnlated  for 

Foand. 

CibHisO^ 

CnHju,0,*CO'CH,. 

(i).     (ii).     (iii).     (iv). 

Mol.  wt.  =  230 

362 

324  318    386    365. 

The  percentage  of  acetyl  was  determined  by  saponifying  the  com* 
pound,  either  by  boiHng  with  alcoholic  potash,  or  by  heating  with 
it  in  a  sealed   tube  at   130°.      Water  was  added  to  the  product, 

*  For  the  molecular  weight  determination  in  benzene  solution,  we  are  in^^bted  ta 
the  kindness  of  Mr.  H.  Jfickson,  B.  A,,  pownin^  College. 

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WOOD,  SPIYSY,   AND  KA8TKBFIELD :  CANNABIKOL.     PART  I.      27 

and,  after  the  alcohol  had  been  boiled  off,  the  solution  was  made 
strongly  add  with  phosphoric  acid,  and  steam  distilled  until  the  dis- 
tillate no  longer  had  an  acid  reaction.  The  distillate  was  then  titrated 
with  aenu-normal  caustic  soda  solution. 

1'6  gave  acetic  acid  equivalent  to  8'85  c.c.  N/2  NaOH  solution. 
^•0    n  „  „  52-4  c.c. 

Calcukted  for  Galcnlated  for 

Ci^HuOi.  CnHaOj'CO'CH,.  Found.^ 

Afistyi-lS-T  per  cent.  12-2  11*9,  12*5. 


Cannabinoly  OjiH^Oj. 

The  residaes  left  in  the  distilling  flasks  in  the  above  acetyl  determi- 
nations were  extracted  with  ether.  The  ethereal  solution  was  dried 
over  cakdam  chloride,  the  ether  distilled  off,  and  the  residue  distilled 
onder  diminished  pressure,  when  practically  the  whole  passed  over  at 
^^nnderSO  mm.  preesure;  the  distillate  was  an  almost  colourless  oil, 
which,  on  cooling,  set  to  a  transparent  resin.  A  second  preparation 
was  made,  and  both  were  analysed. 

01880 gave  0-6687  COg  and  01446  HjO.    0«81-5  ;  H  =  8-6. 
0-1716    „    0-5100  CX)2    „    01300  HgO.     C-8M;H=:8-4. 
CqHs^O,  requires  C»81-3  ;  H  =  8*4  per  cent. 

The  molecular  weight  was  found  by  the  freezing  point  method  in 
glacial  acetic  acid  solution. 

0-5876  gram,  in  20  grams  of  glacial  acetic  acid,  gave  a  depression 
of  0-380°. 

0-6260  gram,  in  20  grams  of  glacial  acetic  add,  gave  a  depression 
of  0-390°. 


Calculated  for 

CbH„0^ 

Found. 

1.  wt.-310. 

310,  313, 

The  compound  is  optically  inactive. 

Oitidaiion  qf  TfinitroccmncUnnol  with  Nitric  Acid, 

One  hnndred  and  twenty  grams  of  trinitrocannabinol  was  dissolved 
m  300  0.C  of  hot,  fuming  nitric  acid,  and  gently  boiled  for  5  hours 
^  a  lefloz  apparatus,  more  acid  being  added  from  time  to  time,  until 
>A  ^  700  cc.  had  been  used.  On  pouring  the  product  into  water, 
70  grams  of  a  yellow,  waxy  precipitate  separated,  and  from  this 
36  grams  of  nitrocannabino-lactone  (ozycannabin)  were  obtained  on 
treatment  with  alcohol,  Xbe  filtrate  from  the  above  yellow  precipitate 

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2ft     WOOD,  SPIVBY,  AND  EASTERFIELD :  CANNABINOL.      PART  I. 

smelt  strongly  of  yalerio  acid,  and  contained  normal  caproio,  valerio, 
and  butyric  acids,  possibly  also  propionic  acid,  together  with  non- 
volatile acids.  Substantially  the  same  products  were  obtained  by 
the  oxidation  of  crude  cannabinol  with  nitric  acid. 

Examination  qf  the  Volatile  Fatty  Acide. 

The  volatile  acids  were  removed  from  the  above-mentioned  acid 
mother  liquor  by  steam  distillation,  and  the  distillate  neutralised 
with  sodium  carbonate  and  evaporated  to  dryness ;  on  acidifying 
with  dilute  sulphuric  acid  and  extracting  with  ether,  12  grams  of  the 
mixed  acids  were  obtained.  These  were  fractionated  with  the  follow- 
ing results. 

105— 160°=  2-2  grams.  170— 180°=  1-2  grams. 

160— 170°=0-9      „  180— 195°=3-9      „ 

Above  195°=  1-86  grams. 

From  the  fraction  150 — 170°,  normal  butyric  add  was  isolated  by 
means  of  its  calcium  salt,  which  was  purified  and  analysed,  with  the 
following  results. 

00730  lost  0-0037 H^O at  135° and  gave  0-0418 OaSO^.    H3O « 7-8 ; 
Ga»16-9. 
(C4H90j)jCa + HgO  requires  HjO  =  77.    Ca  =  172  per  cent. 

The  valeric  add  in  the  fraction  180 — 195°  was  separated  as  the 
valeranilide  which  melted  at  60°  (uncorr.),  and  on  analysis  gave  the 
following  results. 

00660  gave  01795  00^  and  00515  H^O.    0=74-2  ;  H  =  8-7. 
01998    „     13*6  C.C.  moist  nitrogen  at  20*5°  and  767  mm.    N  =  7*8. 
CiiHijNO  requires  C  =  74*6 ;  H  =  85  ;  N  =  79  per  cent. 

As  the  anilide  of  normal  valeric  acid  has  not  been  described,  it  was 
prepared  from  a  sample  of  normal  valeric  acid  boiling  at  186 — 186°, 
and  was  found  to  melt  at  61°  (uncorr.).  Admixture  of  the  anilide 
obtained  from  the  fraction  180 — 195°  with  the  anilide  from  normal 
valeric  acid  did  not  depress  the  melting  point  of  the  latter.  The  acid 
in  this  fraction  is,  therefore,  normal  valeric  acid. 

The  fraction  boiling  above  195°  was  converted  into  the  anilide  which, 
after  many  crystallisations  from  light  petroleum,  melted  at  93*^ 
(uncorr.).  The  analytical  numbers  were  slightly  low  for  a  oapro- 
anilide,  and  lack  of  material  prevented  further  purification.  KornoLal 
caproanilide  melts  at  95°,  and  since  it  has  been  shown  that  the  lower 
acids  belong  to  the  normal  series,  it  can  hardly  be  doubted  that  the 
acid  obtained  from  this  fraction  is  normal  caproic  acid. 

In  a  similar  examination  of  a  much  larger  quantity  of  the  fatty 

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WOOD,  SPIVEY,  AND  EASTERPIELD:  CANNABINOL.      PART  I.      29 

adds  obtained  by  oxidation  of  crude  cannabinol  with  nitric  acid,  the 
same  acids  were  obtained.  Normal  butyric  acid  was  identified  by  its 
caksinm  salt,  normal  valeric  acid  by  its  anilide,  and  caproic  acid  by  its 
silver  salt. 

The  fraction  150 — 170^  was  also  examined  for  isobutyric  acid 
(b.  p.  155'')  by  the  method  used  by  Y.  Meyer  and  Hutzler  (Ber.,  1897, 
2519),  but  as  no  trace  of  acetonio  acid  could  be  detected  after  oxida- 
dation  with  potassium  permanganate,  isobutyric  acid  is  evidently 
absent. 

Gaproic  add  was  also  found  in  the  product  of  the  oxidation  of 
crude  cannabinol  by  chromic  acid  mixture,  and  by  potassium  per- 
manganate solution. 

In  each  case,  the  silver  salt  was  recrystallised  until  the  analytical 
results  were  constant.  A,  From  chromic  acid  mixture  oxidation. 
B.  From  potassium  permanganate  oxidation.  C.  From  nitric  acid 
oxidation. 

f  01459  gave  0-1745  00^  and  00648  H^O.     C  =  325 ;  H  «  4-9. 
-^•101650    „    00800  Ag.    Ag  =  48-5. 
B.     01070    „    00515  Ag.     Ag=i481. 
0.     0-2383    „     01158  Ag.     Ag  =  48-6. 
CjHijCOjAg  requires  0  -  323  ;  H  =  4-9 ;  Ag  =  48  3  per  cent. 

IfUrocai'mabmo4{icUma  (oxycannabin), 

C„H„NO,-NO,-CeH,(OH,)<:^|^0  (3). 

(1)  ^ 

The  preparation  of  this  substance  from  trinitrocannabinol  has  already 
been  described ;  it  can  be  obtained  more  conveniently  by  the  following 
method.  Crude  cannabinol  is  dissolved  in  three  times  its  weight  of 
glaeial  acetic  acid,  warmed  to  100°,  and  nitric  acid  (sp.  gr.  1*42)  slowly 
dropped  in  from  a  burette  in  the  proportion  of  1  c.a  of  nitric  acid  for 
each  gram  of  cannabinol ;  the  solution  is  then  boiled  gently  for  half 
an  houTy  more  nitric  acid  is  added,  and  the  boiling  continued  for 
8 — 10  hours,  nitric  acid  being  added  whenever  the  oxidation  slackens, 
50  grams  of  crude  cannabinol  require  in  all  300 — 400  c.c.  of  nitric 
aoid.  The  product  is  then  poured  into  water,  and  the  nitrocannabino- 
lacione  separated  as  before  3  the  yield  is  15 — 20  per  cent,  of  the  crude 
eaonabinol  used.  When  purified  by  repeated  crystallisation  from  al- 
cohol, it  is  obtained  in  very  faintly  yellowish  needles  melting  at  178° 
(unnnrr.),  and  is  not  changed  by  sublimation.  On  exposure  to  light,  it 
gradoally  assumes  a  reddish  tinge.  It  is  soluble  in  alcohol,  acetic 
acid,  benxefue,  and  concentrated  nitric  acid.  These  properties  show 
that  it  is  identical  with  the  oxycannabin  of  Bolas  and  Francis 
(loe.  et^.),  and  of  Donstan  and  Henry  {loe.  cU.).    Five  samples  were 

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1 01 

dJoi 

1 0-1 


30     WOOP,  SPIVBT,  AND  EASTBRFIBLD :  CANNABINOL.     PABT  h 

analysed.  A.  Purified  by  sublimation.  B.  Precipitated  from  the 
potassium  salt.  C.  Crystallised  from  dilute  acetic  acid.  D.  From 
alcohol.    £.  From  trinitrocaxmabinol,  and  orystailiaed  from  aloohoL 

A.  01478  gave  0-3225  CO,  and  0-0663  Ufi.  C  =  59-5 ;  H^SO. 

B.  01313    „     0-2852  COg    „    0-0580  H,0.  C  =  69-2;  H-4-9. 

C.  0-1195    „    0-2615  COg    „    0-0582  H,0.  C  =  69-7;  H^5-4. 
[01330    „    0-2900  GO,    „    00605  H,0.  C-=59-5;  H  =  61. 

'1615    y,    8-8  c.c.  moist  nitrogen  at  2P  and  772  mm.  N «»  6*3. 

•1415    „    8-0        „  „         17°   „   764    „    N  =  6-6. 

E.    0-1155    „    6-5        „  „         19°  „   750    „    N«=6-4.^ 

CjiHiiNO^  requires  C  =  597 ;  H  «=  5-0 ;  N  =  6-3  per  cent 

CjjjjH^o^jOy  (Bolas  and  Francis)      „      C  =  600 ; H  =  5-0 ; N  =  7 -0      „ 
CioHi^^04(Dunstan  and  Henry)     „      C  =  57-7;H  =  4-8;N  =  6-7      „ 

The  molecular  weight  was  determined  by  the  f  reeaing  point  method 
in  gladal  acetic  acid. 

0*4313  gram,  dissolved  in  20  grams  glacial  acetic  acid,  lowered  the 
freezing  point  0-375°. 

Mol.  wt.  calc.  for  CuH^NO^  -  221.    Found  «  226. 

Nitrocannabino-lactone  is  insoluble  in  cold  aqueous  alkalis,  but 
dissolves  on  boiling  for  a  few  minuteSi  and  is  not  precipitated  on 
dilution  with  water;  the  addition  of  mineral  acids,  however,  pre- 
cipitates it  unchanged.     Its  salts  are  prepared  as  follows. 

FoUunum  salt — This  salt  separates  in  slender,  pale  yellow  needles 
on  mixing  saturated  solutions,  in  absolute  alcohol,  of  the  lactone  and 
caustic  potash. 

•    01197  gave  0-0375  K^SO^.     K  =  14*l. 

CiiHijNOgK  requires  K- 14*0  per  cent. 

Silver  aaU. — ^Prepared   by  adding  silver    nitrate    to  an    aqueous 
solution  of  the  potassium  salt. 

0-1322  gave  0-0409  Ag.    Ag  -  30-9. 

CnHjjjNOgAg  requires  Age«31*3  per  cent. 

'  An  attempt  was  made  to  obtain  the  ethylic  salt  by  boiling  the 
silver  salt  with  ethylic  iodide ;  silver  iodide  separated,  but  on  extracting 
the  product  with  boiling  alcohol,  nothing  but  unaltered  nitrocaniiabixio- 
lactone  was  obtained. 

The  lactone  was  treated  with  aqueous  ammonia,  sp.  gr.  0-88,  and 
with  saturated  alcoholic  ammonia,  both  at  the  ordinary  temperature, 
and  in  sealed  tubes  at  100°.  In  each  case,  nothing  but  the  unaltered 
lactone  could  be  recovered.  Failing  to  obtain  an  amide,  an  at- 
tempt was  made  to  prepare  the  anilide,  but  this  also  was  unsuooeesf  ul. 


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WOOD,  SPIVST»  AKD  EASTERFIELD:  CANNABINOL.      PART  I.     31 

Oxidaiion  qf  Nitro&mnabino-lactane  wUh  dilute  NUric  ^cu£.— Nitro- 
cannabino-lactone  (4  grams)  was  heated  with  25  per  cent,  oitric  aoid 
(80  e.c)  at  185°  for  8  hours,  and  the  liquid,  on  stirring,  deposited  a 
oolonrless,  crystalline,  sparingly  soluble  acid ;  this,  after  recrystallisa- 
tion  from  hot  water,  melted  at  229 — 230°  (uncorr.).  The  weight  of 
the  recrystallised  acid  was  I'l  grams. 

Analysis  shows  that  the  substance  has  the  formula  Oi^H^O^, 
which  may  be  deriyed  from  nitrocannabino-lactone  by  the  oxidation  of 
a  methyl  group  to  a  carbozyl  group,  thus 


OOOH-  CeHj(NOj)<^«j!>CO. 


^'  {  0. 


This  conclusion  is  strengthened  by  the  fact  that  nitrocannabino- 
lactone,  on  oxidation  with  potassium  permanganate  in  the  cold,  yields 
the  same  product.  A.  Was  prepared  by  oxidation  with  nitric  acid. 
B.  With  potassium  permanganate. 

01053  gave  00360  H^O  and  0  2033  CX),.     C  =  527 ;  H  =  38. 
'1328    „     6 '5  cc.  moist  nitrogen  at  21°  and  750  mm.     N  =  5*5. 
/  01725  gave  00612  H,0  and  03300  00,.     0  =  522 ;  H  =  3-9. 
^'  I  0-1700     „     8-0  C.C.  moist  nitrogen  at  20°  and  765  mm.     N  =  5*4. 
CiiHjNO^  requires  0  *  62-6  ;  H  =  36  ;  N  =  55  per  cent. 

The  acid,  neutralised  with  ammonia,  was  converted  into  silver  salt. 

0-1568  gave  00472  Ag.     Ag ^ 30*1. 

Oi^HgNO^Ag  requires  Aga30'2  per  cent. 

This  acid  must  be  regarded  as  the  nitro-derivative  of  the  cannabino- 
lactonic  add  described  below. 

The  nitric  acid  mother  liquor,  from  which  the  sparingly  soluble  acid 
had  separated,  was  evaporated  to  dryness,  the  residue  dissolved  in  a 
very  small  quantity  of  cold  water,  filtered,  again  evaporated  to 
dryness  and  extracted  with  ether.  The  syrup  left  on  evaporating 
the  ether  gradually  deposited  crystals  which  were  excessively  soluble 
in  water,  alcohol,  ether,  glacial  acetic  acid,  and  ethylic  acetate,  but 
practically  insoluble  in  bensene,  chloroform,  and  light  petroleum.  The 
compound  is  most  satisfactorily  purified  by  recrystallisation  from 
sUong  hydrochloric  acid,  when  it  is  obtained  as  a  colourless,  crystal- 
line powder,  melting  at  228 — 230°  with  much  effervescence,  but  only 
a  slight  discoloration. 

Three  preparations  were  analysed^ 

L  0-0948  gave  0-0188  HjO  and  01478  COj.     0  =  425 ;  H  =.  2-2. 

0-0760    „    3-5  C.C  nitrogen  at  20°  and  760  mm.    N  »  5*5. 
n.  01646    „    0-0302  H^O  and  0-2552  OOj.    0  =  42-3  j  H  =  20. 
IDL  01775    „    0-0325  HgO    „    02754  00^     0  =  42-3;  H  =  20. 
The fomuU  C^HjNOjT^quires  O  =  42-3 ;  H  =  20 ;  N  =  5-5. 

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32      WOOD,  8PIVEY,   AND  EASTERFIELD :   GANNABINOL.      PART  t. 

The  acid  is  tribasic^  for  on  titration  with  N/10  soda  and  phenol- 
phthalein,  0*065  gram  required  7*5  c.c.  for  neutralisation.  A  tribasic 
acid  of  the  above  formula  requires  7*65  c.c. 

A  solution  of  the  calcium  salt  of  the  acid  was  prepared  by  neutralisa- 
tion with  chalky  and  from  this,  nitrate  of  silver  precipitated  the  silver 
salt  as  a  primrose-yellow  powder,  slightly  soluble  in  hot  water.  The 
salt  is  feebly  explosive. 

0-113    gave  0004  H^O  and  0079  OO2.  0  =  19-0;  H  =  0-4. 
01565     „    0-1172  AgCl.     Ag  =  56-4. 

CgHgNOgAgg  requires  0=18-7;  H«0-3;  Agc=56-2. 

No  attempt  has  been  made  to  elucidate  the  constitution  of  the  acid ; 
it  is,  however,  difficult  to  account  for  the  formation  of  a  tribasic  acid 
of  the  formula  O^H^NOg  from  nitrotolylbutyrolactone  unless  the  acid 
is  a  hydrozyglyoxylic  acid  of  the  constitution 

00OH-0eHj(0H)(NO2)-0O-000H. 

Amidooannabino-lacUme,  OuHuNHg- O^. — ^This  compound  can  be  ob- 
tained by  the  reduction  of  the  nitrolactone  by  tin  and  hydrochlorio 
acid,  or  by  hydriodic  acid  and  phosphorus^  but  the  latter  is  more 
convenient. 

Ten  grams  of  the  nitrolactone  dissolved  in  40  c.c.  of  glacial  acetic  acid 
was  boiled  with  30  c.c.  of  hydriodic  acid  of  sp.  gr.  1*6  and  5  grams  of 
phosphorus  for  2  or  3  hours,  the  colourless  solution  on  cooling  deposit- 
ing crystals  of  the  hydriodide  of  the  base,  and  a  further  quantity  of 
the  base  was  obtained  by  pouring  the  strongly  acid  mother  liquor 
into  water.  On  dissolving  the  hydriodide  thus  obtained  in  boiling 
water,  dissociation  occurs,  and  the  free  base  crystallises  out  on 
cooling. 

Amidocannabino-lactone  crystallises  readily  from  hot  water  in  long, 
white  needles  melting  at  119^  (uncorr.).  Two  preparations  were 
analysed.  A.  Prepared  by  hydriodic  acid  and  phosphorus.  B.  By 
tin  and  hydrochloric  acid. 

•1260  gave  0-3200  00^  and  0-0770  H^O.     0  =  693 ;  H  =  6-8. 
•1140     „    0-2895  OOj    „    00720  H^O.     0  =  69-2;  H  =  7-0. 
•1826     „     11-5  C.C.  moist  nitrogen  at  22""  and  770  mm.   N  =  7'2. 
B.     00795     „     0-2005  OOj  and  00500  HjO.     0  =  68-8 ;  H  «  70. 
OuHi3^0j  requires  0  =  691 ;  H  =  68 ;  N  «  7-3  per  cent. 

The  hydriodide  was  also  analysed. 

0-1957  gave  01420  Agl.    I  =  39^2. 

OjiHii08'NH3,HI  requires  1  =  398  per  cent. 

The  platinoohloride  was  prepared  by  dissolving  the  base  in  strong 
hydrochloric  acid  and  adding  platinic  chloride  solution.  Two  specimens 
were  analysed. 

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roi 

A.-{01 
(.01 


WOOD,  SPIVET,   AND  SASTERFIELB :  CANNABINOL.      PABT  I.      33 

01200  gave  0-0296  Pt.     Pt  =  24-7. 
0-2594    „     00636  Pfc.     Pt  =  24-5. 

(CiiHiiOg'NH,)yH,Pt01e  requires  Pt  =  24-6  per  cent. 

The  base  was  readily  diazotised,  and  an  attempt  was  made  to 
prepare  cannabino-lactone  from  it  by  Friedlander's  method,  bat  no 
8atisfsct<»7  prodact  could  be  obtained. 

Oaumbino-lactone  was,  howeyer,  easily  obtained  through  the  iodo- 
laetone,  whose  preparation  is  given  below. 

Iodoainnabino4aeUmB,  CHj*  CJBi^l<^^J^<K).—Ten  grams  of  amido- 

cannafalno-lactone  was  dissolved  in  25  c.c.  strong  hydrochloric  acid, 
75  cc  water  added^  and  the  solution  diazotised  by  the  addition  of 
4*5  grams  of  sodium  nitrite  dissolved  in  15  c.c.  of  water,  the  tempera- 
ture being  kept  within  a  few  degrees  of  the  freezing  point.  12*5 
grams  of  potassium  iodide  in  25  cc.  water  was  then  added,  and  the 
mixture  heated  on  the  water  bath  until  evolution  of  nitrogen  ceased ; 
the  acid  liquor  was  then  poured  off,  and  the  solid  residue,  after  treat- 
ment with  solution  of  sodium  thiosulphate  to  remove  free  iodine,  was 
repeatedly  crystallised  from  dilute  acetic  acid.  The  yield  was  10  grams. 
The  iodolactone  forms  almost  colourless  crystals  melting  at  137*5° 
(uncorr.),  insoluble  in  water,  but  easily  soluble  in  alcohol  and  acetic 
scid ;  it  sublimes  very  readily. 

0*2370  gave  0*3825  OOg  and  0*0803  H^O.     0 » 440 ;  H - 3-8. 
0*2785     „    0*2145  Agl.    1-41*6. 

CuHiiI02  requires  0  =  43*7 ;  H  »  3*6 ;  I «  420  per  cent. 

SUwr  Salt. — A  solution  of  the  potassium  salt  was  obtained  by 
satorating  alcoholic  caustic  potash  solution  with  the  iodolactone,  and 
sfter  precipitating  the  excess  of  lactone  by  water,  silver  nitrate  was 
added  to  the  filtrate.  The  silver  salt  was  precipitated  as  an 
amorphous  powder  which  became  crystalline  on  standing.  It  is 
•dable  in  hot  water,  but  cannot  be  recrystallised  without  decom- 
position. 

0*2430  gave  0*13  ]  5  Ai^L     Ag  »  24*9 

Oj^jjIOsAg  requires  Aga  25*3  per  cent. 

C«ifiaKno4ac<<ws,CH.'CgH4<^^C>CO.— The  iodolactone  is  dis- 

solTsd  in  hot  alcoholic  potash  solution  and  the  solution,  diluted  with 
water,  is  reduced  with  2*5  per  cent,  sodium  amalgam.  No  hydrogen 
is  evolved  until  almost  the  theoretical  amount  of  amalgam  has  been 
added,  but  it  is  found  advantageous  to  use  a  considerable  excess  of  the 
reducing  agent  in  order  to  ensure  the  complete  removal  of  iodine.  After 
the  alcohol  has  been  removed  by  boiling,  the  alkaline  solution  is  acidified 
yOL.  LXXV.  Digitized  by^oogle 


34     WOOD,  SPIVET,  AND  EASTEBFIELD:  CANNABINOL.      PART  I. 

by  sulphuric  acid^  and  steam  distilled  until  the  distillate  no  longer 
becomes  turbid  on  adding  a  strong  solution  of  potassium  carbonate. 
The  lactone  is  obtained  by  salting  out  the  distillate  with  potassium 
carbonate,  and  extracting  with  ether ;  the  oily  residue  left  on  evapo- 
rating the  ether  distilled  almost  to  the  last  drop  at  290*5^  (unoorr.) 
under  a  pressure  of  768  mm.  When  purified  by  redistillation  under 
diminished  pressure,  it  was  obtained  as  a  colourless,  highly  refracting 
liquid  of  sp.  gr.  at  20^20°  -1-0833,  and  boiling  at  126^  (unconr.) 
(20  mm.).  The  yield  of  pure  cannabino-lactone  from  the  iodolactone 
amounts  to  86  per  cent,  of  the  theoretical. 

01105  gave  0-3056  00,  and  0-0700  HjO.     0  =  74-9 ;  H  =  7-0. 
CiiH^2^a  requires  0  =  75 "0 ;  F  =  6-8  per  cent. 

The  lactone  dissolves  slowly  in  aqueous  solution  of  caustic  alkalis, 
and  is  reprecipitated  by  carbon  dioxide.  So  great  is  the  tendency  to 
lactone  formation  that  a  current  of  steam  slowly  removes  the  lactone 
from  its  solution  in  excess  of  caustic  potash. 

Cannahinolact(mieAcid,(XyOK*0f;K^<^^  grams  of 

cannabino-lactone,  dissolved  in  hot  aqueous  potash,  was  treated  with  41  -4 
grams  of  potassium  permanganate  dissolved  in  1000  c.c.  of  water,  and 
the  mixture,  after  being  boiled  for  9  hours,  was  decolorised  by  a  few 
drops  of  alcohol.  The  filtrate  from  the  manganese  dioxide,  when 
evaporated  to  200  c.c.  and  acidified  with  hydrochloric  acid,  deposited 
10*6  grams  of  a  pearly-white,  crystalline  compound,  which,  after  re- 
ci-ystallisation  from  hot  water,  was  obtained  in  long  needles  melting 
at  203^  (uncorr.).  The  yield  is  88  per  cent,  of  the  theoretical.  Two 
samples  were  analysed. 

01371  gave  0-3205  00,  and  00636  H,0.    0  =  638 ;  H  =  5-2. 
01380    „    0-3250  00,    „    0-0626  H,0.     0  =  64-2;  H  =  50- 
OuHjqO^  requires  0  =  64-1 ;  H  =  4-9  per  cent. 

The  lactonic  acid  is  soluble  in  about  86  parts  of  boiling  water,  very 
sparingly  in  cold  water,  and  easily  in  alcohol. 

Fbktsnum  Salt, — Prepared  by  adding  alcoholic  potash  to  an  alcoholic 
solution  of  the  lactonic  acid. 

0-2296  gave  00826  K^SO^.     K  =  16-1. 

Oi^HqO^K  requires  K  =  16-0  per  cent. 

The  silver  salt  was  found  to  contain  33-8  per  cent.  Ag.  OjjHgO^Ag 
requires  34*6  per  cent. 

The  ethylic  salt  was  prepared  by  boiling  the  lactonic  acid  for  6  hours 
with  a  3  per  cent,  solution  of  hydrogen  chloride  in  absolute  alcohol. 
After  recrystallisation  from  dilute  alcohol,  it  melted  at  105^  (uncorr.), 
and,  on  analysis,  gave  the  following  numbers. 

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WOOD,   SPIVmr,    AND   EA8TBRFIELD;  CANNABINOL.      PART  I.      35 

0-0861  gave  02095  COg  and  0-0484  H,0.     C  =  664 ;  H  =  6-2. 
01608     „     0-3905  CO,    „    00890  HgO.     C  =  66-2;  H  =  61. 
^n^A-  CgHj  requires  C  =  667  ;  H  =  60  per  cent. 

Fusion  of  Cafmabino-lactonic  Acid  toith  Potash. 

4*4  grains  of  the  lactonic  add  was  fused  with  25  grams  moist  caustic 
potash  at  286*^  (in  a  bath  of  boiling  )9-naphthol).  The  reaction  is 
completed  ahnost  instantaneously  at  this  temperature,  but  proceeds 
with  extreme  slowness  at  220^.  The  melt,  on  being  dissolved  and 
acidified  with  dilute  sulphuric  acid,  gave  3*4  grams  of  a  crystalline 
precipitate,  which,  after  several  recrystallisations  from  dilute  alcohol, 
sablimation,  and  a  further  recrystallisation,  melted  above  300°,  and 
sublimed  without  decomposition. 

0-11 33  gave  02392  00^  and  00400  H^O.     0  =  576 ;  H  =  39. 
OgH^O^  requires  0  =  57*8  ;  H  =  36  per  cent. 

The  analysis  and  physical  characters  agree  with  those  of  isophthalic 
acid. 

Its  methylic  salt  melted  at  64°  (unoorr.),  and  boiled  at  280—282° 
(unoorr.)  (Baeyer  gives  64—65°,  Atmalen,  1873,  106,  340).  The  salt, 
on  analysis,  gave  the  following  numbers. 

0-1084  gave  0-2445  GO^  and  00518  H^O.     0  =  615;  H  =  5-3. 
0-1060     „     0-2395  COj    „    00510  H,0.     0  =  61-7  ;  H  =  53. 
O^H4(COOOH3),  requires  0  =  61-9  ;  H  =5-1  per  cent. 

Potash  Fusion  of  Cann<Mno4actone  with  Potash, 

The  conclusions  to  be  drawn  from  the  fusion  of  cannabino-lactonic 
acid  are  supported  by  the  potash  fusion  of  cannabino-lactone  (0*9  gram) 
with  moist  caustic  potash  (15  grams)  at  300°  to  320°,  which  yields 
metatoluic  add. 

The  reaction  took  place  slowly,  and  the  melt,  which  was  very  dark 
in  colour,  was  dissolved,  acidified  with  sulphuric  acid,  and  extracted 
with  ether,  Ac.,  in  the  usual  way.  After  purifying  the  product  by 
ciystaUisation  from  water  and  animal  charcoal  03  gram  was  obtained. 
It  began  to  melt  at  108°,  but  was  not  completely  melted  until  200°.  It 
was  accordingly  steam  distilled,  and  the  crystals,  which  separated  in  the 
distillate,  were  now  found  to  melt  at  110°  (uncorr.).  Jacobsen  {Ber.f 
1881,  14,  2349)  gives  the  melting  point  of  metatoluic  acid  as  110-5°. 
The  mother  liquor  from  which  the  metatoluic  acid  had  been  removed 
by  steam  distillation,  on  being  evaporated  to  dryness,  dried  at  150°, 
and  then  recrystallised  from  water,  gave  isophthalic  acid,  which 
melted  above  300°,  and  sublimed  without  decomposition  ;  this  was, 
no  doubt,  produced  frdm  the  metatoluic  acid  by  further  oxidation. 

_.  „„  p_2oogle 


36  KIPPING  AND   POPE:  CHARACTERISATION  OF 


Reduction  qf  CannalnnO'laetonie  Acid. 

The  lactonio  acid  was  reduced  by  heating  with  hjdriodic  acid  and 
phosphorus  in  a  sealed  tube  at  190%  and  the  product,  after  two 
recrystallisations,  melted  at  about  210°.  As  the  limited  quantity 
of  the  substance  did  not  allow  of  further  purification,  it  was  analysed. 
The  result  leaves  no  doubt  that  it  is  the  expected  metacarbozy- 
phenylbutyrsc  acid. 

(1)  COOH-C^H^-QgHa-OOOH  (3). 

01298 gave  03044  COg  and  00696  H^O.     0  =  640 ;  H- 59. 
OiiH^O^  requires  0  =  63-6  ;  H»  5*8  per  cent. 

Uniyersitt  Chbmioal  Laboratory, 
Cambridob. 


IV. — Characterisation  of  JRacemic  Compounds. 

By  Fbedbbio  Stanley  Kipping  and  William  Jackson  Pops. 

Wb  have  previously  shown  (Trans.,  1897, 71,  989)  that  the  results  of  the 
study  of  a  number  of  externally  compensated  substances  indicate  that 
only  one  method  is  at  present  of  really  practical  use  for  characterising 
solid  racemio  compounds,  that,  namely,  which  is  based  on  the  deter- 
mination of  the  crystalline  forms  of  the  optically  active  and  externally 
compensated  materials ;  and,  in  accordance  with  this  conclusion,  we 
defined  crystalline  racemic  and  pseudoracemio  compounds  from  a  purely 
crystallographic  standpoint  {loe.  eit.,  993).  But  the  crystallographic 
constants  of  an  organic  substance  are  not  always  determinable  with 
ease  and  completeness ;  hence  the  establishment  of  other  criteria  of 
racemism  is  a  matter  of  considerable  importance. 

Now,  liebisch  has  shown  (AnnaieHf  1895,  286,  140)  that  a  com- 
parison of  the  densities  of  the  optically  active  and  externally  compen- 
sated compounds  affords  a  very  simple  method  for  the  determination  of 
racemism  (compare  Walden,  B&r.^  1896,  29,  1692);  unfortunately, 
however,  the  results  of  the  experimental  determination  of  a  difference 
between  two  density  constants,  especially  when  this  difference  is  very 
small,  as  it  frequently  may  be,  can  hardly  be  considered  so  conclusive 
as  those  derived  from  the  much  more  complex  series  of  constants 
constituting  the  crystallographic  properties. 

This  difficulty  of  ascertaining,  except  by  crystallographic  deter- 
minations, whether  certain  substances  are  really  racemic  on  the  one 
hand,  or  merely  pseudoracemio  or  externally  compensated  mixtures  on 

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RACEMIC  COMPOUNDS.  3? 

the  other,  baa  led  to  attempts  being  made  to  devise  simpler  methods  for 
the  determination  of  racemism.  Thus,  Ladenburg  {Ber„  1894,  27, 
3065)  formolates  "  eine  allgemeine  Methode^  am  Qemenge  enantio- 
morpher  Korper  von  racemischen  Yerbindongen  zu  unterscheiden. 
Sobald  es  gelingt,  die  in  Frage  stehende  Snbstanz,  die  wenigstens 
einen  kleinen  Ueberschass  der  einen  drehenden  Modification  enthalten 
moss,  dnrch  Behandlnng  mit  inactiren  Korpem  in  Fractionen  yon 
▼eriLndertem  Drehnngsvermogen  zu  Terwandeln,  liegt  stets  eine 
Yerbindnng  Tor." 

Now  this  method,  if  really  applicable,  should  prove  of  great  value, 
but  inasmuch  as  Ladenburg  adduces  no  experimental  evidence  sup- 
porting its  validity  as  a  means  of  discrimination,  but  uses  it  without 
further  inquiry  in  order  to  decide  as  to  the  racemic  nature  of 
externally  compensated  coniine,  the  conclusions  based  on  its  use  cannot 
be  regarded  as  in  any  way  decisive. 

Moreover,  the  method  is  arrived  at  by  means  of  a  curiously 
falladous  piece  of  reasoning,  for,  just  before  the  above  quotation, 
Ladenbuzg  writes :  ^  es  ist,  wie  ich  glaube,  eine  bisher  ausnahmlos 
bestiltigte  Thatsache,  dass  enantiomorphe  KQrper  stets  die  gleiche 
Lbdiehkeit  besitaen  und  daher  auch  in  Yerbindung  mit  inactiven 
Stoffen  nicht  duroh  Erystallisation  oder  partielle  FalluDg  getrennt 
werden  konnen." 

Kow  there  seems  not  the  least  justification,  experimental  or 
theoretical,  for  the  deduction  which  Ladenburg  draws  from  the 
fact  of  the  equal  solubility  of  the  two  enantiomorphously  related 
substances,  namely,  that  a  mixture  of  unequal  quantities  could  not  be 
separated  by  crystallisation  or  partial  precipitation.  There  is,  in  fact, 
no  evidence  that  an  inactive  non-racemic  mixture  has  the  same 
solubility  as  either  of  its  active  components  and  if  its  solubility  be 
greater,  then,  on  concentrating  a  solution  containing  such  a  non- 
raoemic  mixture  together  with  excess  of  one  enantiomorph,  at  constant 
temperature,  that  excess  would  crystallise  first,  leaving  material  of 
lower  specific  rotation  in  solution  ;  a  continuation  of  this  process  would 
ultimately  afford  a  mother  liquor  containing  an  inactive  non-racemic 
mixture.  The  solution  would  then  go  on  depositing  dextro-  and  l»vo- 
material  in  equal  proportion  as  evaporation  proceeded,  casual  dis- 
turbanoes  of  equilibrium  such  as  always  occur  in  a  crystallising 
solution  being,  of  course,  disregarded.  Obviously,  therefore,  any 
arguments  based  upon  our  present  knowledge  of  the  laws  governing 
soIubiUty  should  have  led  Ladenburg  to  a  conclusion  diametrically 
opposed  to  that  at  which  he  actually  arrived. 

The  question  of  the  racemic  nature  of  externally  compensated  coniine 
has  lately  been  again  considered,  and  Kiister  {Ber.,  1898,  31,  1847), 
arguing  from  tj|te  solubility  products  of  the  various  isomerides,  con- 

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38  KIPPING  AND  POPE:  OHARACTTBRISATION  OF 

eludes  that  a  large  part  of  the  inactive  bubstance  exists  in  solution  in  a 
raoemic  condition.  Although  this  conclusion  may  be  true,  yet, 
inasmuch  as  no  case  has  been  investigated  in  which  the  solubUity 
values  indicate  that  no  raoemism  occurs  in  the  solution,  or  in  the  solid 
state,  as  the  case  may  be,  Kiister's  method  cannot  be  accepted.  A 
hypothesis  founded  upon  one  set  of  phenomena  often  gives  valuable 
indications  as  to  the  direction  in  which  work  should  be  done  in  con- 
nection with  the  examination  of  a  second  set  of  phenomena,  but  these 
are  merely  indications,  and  require  experimental  verification  before  the 
hypothesis  can  be  extended  so  as  to  cover  the  new  ground.  The  cases 
dealt  with  by  Kiister  are  instances  in  which  the  ordinary  solubility 
laws  applying  to  two  mutually  inactive  solutes  are  not  followed ;  when 
a  case  is  found  amongst  externally  compensated  substances  in  which 
the  solubility  determinations  indicate  the  non-existenoe  of  a  racemic 
compound  in  solution,  Kiister's  method  will  become  of  practical  value. 
Until  then,  however,  it  must  be  classed  with  Ladenburg's  method  as  an 
untried  one. 

In  order  to  ascertain  the  accuracy  or  otherwise  of  Ladenburg's 
argument,  we  have  examined  three  cases  experimentally;  those, 
namely,  of  sodium  ammonium  tartrate,  sodium  potassium  tartrate, 
and  potassium  hydrogen  tartrate. 

Sodium  Ammonium  Dextro-  and  LcBvo-tartraiea, 

An  externally  compensated  mixture  of  dextro-  and  levo-sodium 
ammonium  tartrates  is  known  to  be  non-racemic  at  ordinary  tempera- 
tures, but  becomes  racemic  at  and  above  27^  (van't  HofE  and 
Deventer,  £er,,  1886,  19,  2148);  below  this  temperature,  the  salt 
separates  from  solution  as  a  mere  mixture  of  the  two  tartrates. 

Now,  if  Ladenburg's  rule  be  applicable,  on  crystallising  the  sodium 
ammonium  salt  of  racemic  acid  with  an  excess  of  sodium  ammonium 
dextrotartrate  below  27^>  the  successive  fractions  should  have  the 
same  specific  rotation ;  but,  as  a  matter  of  fact,  the  behaviour  of  the 
mixture  on  crystallisation  is  that  which  would  be  expected  from  our 
interpretation  of  the  laws  governing  the  equilibrium  of  such  solu- 
tions. 

In  a  preliminary  experiment,  an  intimate  mixtture  of  25  grams 
of  sodium  ammonium  dextrotartrate  with  5  grams  of  the  corres- 
ponding lisvotartrate  was  made ;  it  was  found  to  have  the  specific 
rotation  [a]i>e +15-60^  in  a  5  per  cent,  solution,  instead  of  the 
calculated  value  [a]  «  + 16*76^  The  mixture  was  dissolved  in  cold 
water  and  set  aside  to  evaporate;  after  several  days,  a  fraction  (1)  aepa- 
rated  and  was  collected,  washed  with  cold  water,  and  dried  in  the  air. 
The  mother  liquor  and  washings  were  mixed  and  set  aside  to  crystallise^ 

„ .gitized  by  VjOOQ  _  _ 


RACEUIO  COMPOUNDS.  89 

when  a  further  separation  (2)  was  obtained ;  this  was  removed  as 
before,  the  mother  liquors  evaporated  to  dryness,  and  the  residue 
collected.  During  the  experiment,  the  laboratory  temperature  never 
rose  above  15° ;  the  weights  and  rotations  of  these  fractions  were  as 
follows. 

Weight  [a]D 

Total  material  30  g.  +  IS-eO"" 

First  fraction,    (1)  8  g,  +23*51 

Second      „        (2)  13  g.  +20-27 

Third        „        (3)  8  g.  0 

Instead  of-  all  the  three  separations  having  the  same  specific 
rotation  as  the  original  mixture,  as  required  by  Ladenburg's  rule,  the 
first  two  fractions  consisted  almost  entirely  of  dextrotartrate,  whilst 
a  5  per  cent,  aqueous  solution  of  the  residue  in  the  mother  liquor  had 
no  observable  rotation  in  a  200  mm.  tube. 

In  order  to  trace  this  process  of  separation  more  carefully,  and  thus 
obtain  further  data,  the  following  experiments  were  made.  A  mixture 
of  26*1  grams  of  sodium  ammonium  dextrotartrate,  with  an  equal 
weight  of  the  salt  obtained  from  racemic  acid,  wiis  made ;  this  mixture, 
having  a  specific  rotation  of  [a]o=  + 11*82°,  was  dissolved  in  water 
and  allowed  to  crystallise  spontaneously  at  the  ordinary  laboratory 
temperature,  which  never  rose  above  18°,  namely,  9°  below  the  tem- 
perature at  which  a  racemic  compound  begins  to  separate.  As  the 
various  deposits  were  obtained,  they  were  separated  by  means  of  the 
filter  pump  (but  not  washed  free  from  mother  liquor)  and  examined, 
the  fractionation  proceeding  in  accordance  with  the  following  scheme 
(next  page). 

The  weights,  w,  and  the  specific  rotations  a,  of  the  various  fractions 
are  given  in  columns  2  and  3  respectively  of  Table  I  (p.  41),  columns 
5  and  6  give  respectively  the  excess  of  dextro-  over  inactive  salt  in  100 
parts  of  the  various  fractions,  and  the  actual  weights  in  grams  of  the 
excess  of  dextro-salt  in  these  fractions. 

The  weight  of  salt  recovered  from  the  52*2  grams  dissolved  was  2to 
»51-25  grams;  the  weighted  mean  specific  rotation  of  all  the 
fractions  is  2u^/2io» +12-20°,  and  if  the  weight  of  salt  taken, 
namely,  62*2  grams  be  substituted  for  2to,  the  mean  specific  rotation 
2ioa/52*2=  +11*98°  is  obtained. 

The  mixture  of  salts  actually  had  the  specific  rotation  [ajo  «  + 1 1*82° 
so  that  within  the  limits  of  the  experimental  errors  unavoidably 
incurred  in  so  long  a  series  of  fractionations,  the  whole  of  the  salt  used 
is  accounted  for. 

The  specific  rotation  of  sodium  ammonium  dextrotartrate, 
Na(NH,)C,H,Oe  +  4H20i 
is  [ajo^  +23*64°,  and  the  first  large  deposit  of  32*1  grams  contaiued 

„.gitized  by  Google 


40 


KIPPINQ  AND  POPS:  CHARACTERISATION   OiT 


P 


to 


d  rf 


I 


C 


r 


I 


►4 


"oo 


■"00 


M 

O 


— to 


to 

-o 


to 


h5 

^ 

«  i 

^ 

J 

» 

V 

i 

^       tCQ 

db 

lO 

00 

« 

•^w 

to 
tp 

"4* 


to 


to 

04 


Digitized  by  VjOOQIC 


KAGEMIO  COMPOUNDS. 
Table  I. 


41 


1.                       2. 

8. 

4. 

6. 

6. 

fnustion. 

to. 

grmms. 

a. 

wa. 

Percentage 

excess  of 

d-aalt 

Weight  of 

excess  of 

(i-salt. 

D. 

1 
1 
\ 

4*86 
8-26 
1-70 

1*60 
4-60 
8-9 

2-5 
6*1 
8-7 

4-16 
8*6 
11*6 

+  28-28 
+  28-28 
+  21*66 

+  28-47 
+  28-12 
+  28-02 

+  22-61 

+10-61 

0 

+  16*62 
-22*40 

+  6-41 

+  112-67 
+  76-60 
+  86*64 

+  86*20 

+  106-86 

+  89-78 

+  66-27 

+  64-11 

0 

+  64-41 
-78-40 
+62-76 

+  98-26 
+  98*26 
+  90-86 

+  99*28 
+  97-80 
+  97*88 

+  96*22 

+46*46 

0 

+  66*66 
-94*76 

+  22-88 

+  4-766 
+  8194 
+  1*660 

+  1-488 
+  4-499 
+  8-798 

+  2-881 
+2*712 
0 

+  2-724 
-8-816 
+  2-666 

210=51*26. 


2u«= +626-29. 


3IP= +26-461. 


????= +12-20'. 
210 


|^= +11-98'* 
62-2 


28*25  grams  of  sodium  ammonium  deztrotartrate  and  3*85  grams  of 
the  isomeric  levo-salt ;  this  corresponds  with  24*4  grams  of  the  sodium 
ammonium deztrotartrate  with  7*7  gramsof  the  inactive  mizturOi  so  that 
nearly  the  whole  of  the  26*1  grams  of  the  dextro-salt  originally 
taken  was  deposited  in  the  first  crop  of  crystals.  After  the  next 
separation,  m^,  from  the  mother  liquor,  27*1  grams  of  the  deztrotar- 
trate had  separated  in  addition  to  inactive  material ;  consequently,  the 
mother  liquor  was  strongly  Isevorotatory,  and  the  next  separation,  m,, 
was  a  ]«vorotatory  one.  Practically,  all  the  excess  of  the  dextro- 
rotatory salt  was  contained  in  the  first  fractions,  A^,  h^,  Ag,  A^,  k^  k^  and 
l^f  which  consisted  almost  entirely  of  this  salt,  but  still  contained 
small  quantities  of  the  inactive  material,  partly  because  the  crystals 
were  not  washed,  and  partly,  no  doubt,  because  of  occluded  mother 
liquor,  which  is  often  present  in  noticeable  quantity.  The  further 
flanges  during  crystallisation  will  be  understood  from  the  tabulated 
results. 

In  a  recent  paper  (Trans.,  1897,  71,  999),  we  have  shown  that  ex- 
temally  compensated  camphorsulphonic  chloride  (Trans.,  1893,63^  560) 
and  camphorsulphonic  bromide  (Trans.,  1895,  07,  359)  are  probably 
peeudoraoemic  ;  consequently,  they  behave,  on  crystallisation,  like  non- 

Digitized  by  VjOOQIC 


42  KIPPIKG  AND  POPK:  CHAHACTBBISATION  OP      ^ 

racemic  compounds  and  the  ethylic  acetate  solutions  of  a  strongly 
dextrorotatory  mixture  of  the  sulphonic  chlorides  deposits^on  evapora- 
tion, part,  or  the  whole,  of  the  excess  of  the  dextro-compound  ;  after 
the  solution  has  thus  become  nearly  or  quite  inactive,  further  crystal- 
lisation affords  deposits  which  sometimes  contain  an  excess  of  one  or 
other  isomeride,  a  behaviour  which  is  obviously  very  similar  to  that  of 
the  sodium  ammonium  tartrates. 


JSodium  Fotaasium  DextrotartraU  and  Racemaie, 

Having  shown  by  the  foregoing  experiments  that  Ladenburg'a 
method  does  not  hold  in  the  case  of  non-racemic  sodium  ammonium 
dextro-  and  Isavo-tartrates,  namely,  in  the  only  test  case  on  which 
the  method  has  yet  been  worked  out,  we  thought  it  advisable  to 
apply  the  same  method  to  a  case  in  which  a  crystalline  racemic  com- 
pound undoubtedly  exists,  in  order  to  ascertain  whether  the  fractional 
separation  occurs  in  a  manner  essentially  different  from  that  observed 
in  the  case  of  a  non-racemic  mixture. 

Sodium  potassium  dextrotartrate  is  isomorphous  with  the^  corre- 
sponding sodium  ammonium  salt  and,  at  temperatures  between  —  6^ 
and  +  41%  forms  a  racemic  compound  with  the  isomeric  Invotartrate 
(van't  Hoff  and  Deventer,  Zeit.  phyaih.  Chem,,  1895,  17,  505)3  it 
therefore  forms  a  racemic  compound  at  ordinary  temperatures.  The 
optically  active  substances  have  the  composition  NaKO^H^O^  +  4H2O, 
whilst  the  composition  of  the  racemate  is  NaEO^H^O^  +  SH^O. 

A  mixture  of  47*4  grams  of  sodium  potassium  dextrotartrate  with 
44*4  grams  of  the  racemate  (molecular  proportions)  was  dissolved 
in  water  and  fractionally  crystallised  as  before  ;  the  scheme  given 
on  the  next  page  shows  how  the  various  fractions  were  collected. 
Table  II  (p.  44)  gives  the  weights,  to,  and  the  specific  rotations,  a,  for 
the  Z>-line ;  columns  5  and  6  give  the  values  corresponding  with  those 
in  Table  I. 

The  specific  rotation  of  the. anhydrous  dextrotartrate,  KNaO^H^O^, 
is  [ajo-"  +29*67°  (Landolt)  ;  that  of  the  mixture  of  47*4  grams  of 
hydrated  dextrotartrate  with  44*4  grams  of  the  racemic  salt  is, 
therefore,  [a]]) » +11*41°.  The  weighted  mean  specific  rotation  of 
all  the  separated  fractions  is 

whilst 

?^= +11*28°. 
91*8 

Digitized  by  VjOOQIC 


RACEMIC  COKPOUNDS. 


A 


►4 

ri 
•0 

3 

OB 


MM 
«■  J? 

c0  m 


^-i^ 


1 


l_r? 


h4      ** 


3 


B 


1^ 


o 


V    to 


Digitized  by  VjOOQIC 


44  KIPPINQ  AND  pope:  CHARACTERISATION   OP 

Tablb  II. 


1 

2. 

8. 

4. 

6. 

6. 

Fraction. 

grams. 

a. 

wa. 

Percentage 

excess  of 

d-aaXt 

Weight  of 

excess  of 

tUmXt 

*i 

9-16 

+  22-08" 

+  202  0 

+  99-78 

+9*126 

h 

10-40 

+  21-77 

+  226-6 

+  98*88 

+  10*280 

h 

7-46 

+  21-66 

+  160*6 

+  97*88 

+  7-266 

K 

4-45 

+  21-26 

+94-6 

+  96*98 

+  4-271 

^ 

8-70 

+  17-60 

+  162-2 

+  79-22 

+  6-891 

h 

7-8 

+  21-86 

+  166-6 

+  96*48 

+  7*628 

h 

12-2 

+  4-68 

+  66-9 

+  81-90 

+  8-864 

mi 

8-8 

-20-00 

-66  0 

-90-84 

-2*981 

mj 

8-4 

+  10-00 

+  84-0 

+  46-17 

+  1*636 

»»3 

6-7 

+  1-86 

+  9-0 

+  6-10 

•     +1*408 

Wl4 

8-7 

0 

0 

0 

0 

We 

9  0 

0 

0 

0 

0 

2ii»=91-26. 


2wo= +1086-4. 

?^=+ll*84^ 
7,w 


SZ>= +47*622 


SZ>=68-684. 


2toa 
91-8 


=  +11*28'. 


The  agreement  between  the  quantities  and  specific  rotations  of  the 
material  taken,  and  the  quantities  and  specific  rotations  of  the 
fractions  recovered,  is  hence  highly  satisfactory. 

From  an  inspection  of  Table  II,  it  is  seen  that  the  successive 
fractions  separating  from  the  solution  decrease  in  specific  rotation, 
that  is  to  say,  they  contain  decreasing  quantities  of  the  deztrotartrate 
in  eiccess  of  the  racemate,  and  ultimately  the  mother  liquors  contain 
nothing  but  pure  racemate.  The  table  also  shows  the  following 
curious  facts :  the  fractions  h,  k,  and  I  contain  48*66  grams  of  the 
deztrotartrate  as  such,  whilst  material  corresponding  with  only  47*4 
grams  was  used;  the  difference  of  1*26  grams,  therefore,  must  be 
ascribed  either  to  experimental  error  or  to  the  fact  that  part  of  the 
racemate  used  was  resolved,  and  the  dextrorotatory  component  de- 
posited here.  That  the  latter  alternative  is  the  true  one  is  shown  by 
the  mother  liquor  becoming  Isovorotatory.  Consequently,  on  crystal- 
lising the  latter,  the  first  deposit,  m^,  is  strongly  IsBvorotatory,  con- 
taining 90*34  grams  of  l»votartrate  to  each  9*66  grams  of  racemate; 
2*98  grams  of  l»votartrate  crystallised  as  such  in  m^,  whilst  the 
solution  only  contained  1*26  grams  excess  of  this  salt.  In  the  end, 
therefore,  50*38  (47*4  +  2-98)  grams  of  dextrotartrate  had  separated 

Digitized  by  VjOOQIC 


RACEMIC  COMPOUNDS.  45 

from  solution  as  such,  or  about  3  grams  more  than  had  been  used  ; 
it  follows,  therefore,  that  a  partial  resolution  of  the  racemate  had 
occurred,  about  6  grams  being  so  resolved.  The  good  agreement  of 
the  sums  of  the  weights  of  salt  separated  from  the  solution  and  the 
mean  rotation  of  the  fractions,  on  the  one  hand,  with  the  weight  of 
salt  and  the  mean  specific  rotation  which  should  have  been  obt^ned, 
on  the  other  hand,  is  proof  that  we  are  not  here  being  misled  by 
experimental  error. 

The  interesting  work  of  Purdie  on  the  resolution  of  lactic  acid  into 
its  optically  active  components  (Trans.,  1893,  63,  1143)  affords  a 
case,  similar  to  the  above,  of  the  resolution  of  a  racemic  compound. 
Baoemic  zinc  ammonium  lactate  crystallises  with  SH^O,  and  when  its 
supersaturated  solution  is  sown  with  a  crystal  of  either  of  the 
optically  active  isomerides,  that  particular  isomeride  separates  in 
crystals  containing  2H2O ;  this  resolution  is  similar  to  that  which 
has  occurred  in  fractions  l^  and  m^  of  our  mixture. 

We  are  thus  led  to  the  following  conclusion  :  a  racemic  compound 
may,  under  certain  conditions,  be  resolved  into  its  optically  active 
components  by  simple  crystallisation,  at  temperatures  at  which  the 
racemic  compound  is  more  stable  than  the  mixture  of  the  two  optically 
active  salts. 

A  comparison  of  Tables  I  and  II  shows  that  the  fractional  crystal- 
Uaation  has  followed  much  the  same  course  in  the  case  of  the  racemic 
compound  as  in  that  of  the  non-racemic  mixture ;  the  separation  of 
the  racemic  compound  from  the  dextrorotatory  one  is,  however,  not 
quite  so  sharp  as  in  the  separation  of  the  non-racemio  mixture. 

Poiasnvm  Hydrogen  Dexiroiartrctte  and  Racemate^  KHC^H^O^. 

In  the  foregoing  cases,  the  inactive  mixture  or  compound  is  more 
soluble  than  either  of  the  active  components;  it  seemed  desirable, 
therefore,  to  investigate  a  case  in  which  the  contrary  is  true.  Such 
a  ease  was  found  on  examining  the  behaviour  of  the  potassium  hydro- 
gen tartrates.  On  crystallising  a  mixture  of  equal  quantities  of  the 
deztrotartrate  and  of  the  racemate,  by  allowing  the  hot  solution  to 
cool,  it  was  found  that  the  mother  liquor  contained  a  salt  of  much 
higher  specific  rotation  than  that  of  the  mixture  deposited;  by 
repeatedly  recrystallising  the  deposit,  the  specific  rotation  of  the 
material  in  the  successive  mother  liquors  remained  nearly  constant, 
and  of  very  much  higher  value  than  that  of  the  crystalline  separations. 
Owing  to  the  sparing  solubility  of  these  two  salts,  they  had  to  be  dis- 
solved in  dilute  ammonia  for  the  rotation  determinationa  The  results 
need  not  be  quoted  in  full,  because  they  were  in  so  many  respects  similar 
to  the  preceding  cases,  and  the  experimental  error  was  greater. 

Digitized  by  VjOOQIC 


n 


46      pope:  crystalline  form  of  iodoform. 

The  ezanunation  of  these  three  cases  shows  that  Ladenburg's  method 
does  not  constitute  a  means  of  discriminating  between  cases  in  which 
a  solid  racemic  compound  is  formed,  and  those  in  which  a  more  inactive 
mixture  is  obtained ;  a  scrutiny  of  Tables  I  and  II  will  show  that  this 
method  gives  practically  the  same  results  with  a  wellniefined  racemic 
compound  as  with  a  non-racemie  mixture. 

It  may  possibly  be  objected,  that,  although  inactive  sodium  am- 
monium tartrate  does  not  exist  as  a  solid  racemic  compound  at 
ordinary  temperatures,  it  may  exist  as  a  racemic  compound  in  solu- 
tion ;  to  make  this  assumption  unsupported  by  experimental  evidence 
is,  however,  unjustifiable,  and  can  only  be  regarded  as  an  expression  of 
opinion. 

Chemistby  Depa&tment,  Chemistbt  Department, 

Uniybrsity  College,  Goldsmiths'  iNSTiruTE, 

Nottingham.  London,  S.E. 


V. — Crystalline  Form  of  Iodoform. 

By  William  Jackson  Pope. 

Up  to  the  present,  no  geometrical  measurements  with  any  pretensions 
to  accuracy  have  been  made  on  crystals  of  iodoform,  the  only  available 
data  consisting  of  two  angles  measured  by  Bammelsberg  {Krytt.-pkyM, 
Chem.,  1882,2, 321) ;  these  measurements  cannot,  however,  be  credited 
with  much  value  since  Eammelsberg  remarks  of  his  crystals  that  *'  die 
Flachen  sind  ziemlich  matt." 

Considerable  difficulty  is  found  in  obtaining  well  developed  crystals  of 
iodoform  using  the  ordinary  organic  solvents  such  as  alcohol  or  benzene. 
Iodoform  is,  however,  fairly  soluble  in  acetone,  and  on  allowing 
the  cold  solution  to  evaporate  spontaneously  at  a  uniform  temperature, 
magnificent,  transparent,  six-sided  tablets  of  iodoform  separate ;  in  order 
to  obtain  the  best  results,  the  acetone  should  be  as  free  from  water  as 
possible.  Even  when  pure,  almost  odourless  iodoform  is  used,  blacken- 
ing occurs  round  the  sides  of  the  vessel,  and  some  product,  probably 
iodacetone,  is  formed  during  the  evaporation  which  excites  to  tears, 
and  powerfully  affects  the  mucous  membrane. 

The  crystals,  which  may  readily  be  obtained  of  a  centimetre  in  dia- 
meter, and  several  millimetres  in  thickness,  are  uniformly  developed, 
and  the  faces  give  very  perfect  reflections  on  measurement.  The 
dominant  form  is  c{lll},  the  pyramid  r{100,  22T}  being  very  much 
smaller ;  the  prisms  p  {TtO}  and  m  {211}  are  rarely  observed  and  are 
always  small  (see  Fig.  1).     The  crystals  are  very  hard  and  brittle,  free 

„.gitized  by  Google 


pope:  crystalline  FaRM  OF  IODOFORM.        4*7 

from  siriations,  and  have  no  noticeable  cleavage ;  they  show  a  six-sided 
internal  growth  of  hexagonal  symmetry  when  allowed  to  grow  rapidly. 

The  normal  hexagonal  optic  axial  interference  figure  is  seen  on  cono- 
seopic  examination  through  the  faees  of  o  {111} ;  the  double  refraction 
is  strong  and  negative  in  sign. 

Bammelsberg  (Joe.  cit,)  determined  the  angles  cr  (111  :  100)^52''  0' 
and  rr  (22T  :  100) ^iG""  30',  gives  the  axial  ratio  a  :  c»- 1  :  M08,  and 
only  observed  the  forms  e{lll}  and  r  {100,  221}. 

Crystalline  system. — ^Hexagonal. 

a:c  =  1  : 1-1084.     a-  93^41'. 

Fonns  observed  c {111}....^ {0001} 

r  {100, 221} {1011} 

pjllO} {2110} 

w{2TT} {OlIO} 

Fig.  1. 

.;....r... 


Tbe  f  oUowing  angular  measurements  were  obtained. 


Asgle. 

Knmber  of 

Limits. 

Mean. 

Calculated. 

er=rlll:100 

38 

51*55'—  52°  r 

5r59'50" 

_ 

fr=100:010 

16 

85  68—88    6 

86    2    0 

86°  2'20'' 

fr=22l:00l 

47 

75  50—  78   6 

76    0  30 

76    0  20 

rr=IOO:010 

15 

98  54—  94    8 

98  58  10 

98  57  40 

»r=riO:010 

22 

46  43—47    2 

46  57  80 

46  58  50 

fT=22l:100 

84 

46  20  —  46  25 

46  23  40 

46  24   0 

fT=22i:100 

19 

133  82  —183  41 

138  36  10 

138  36   0 

g»=lll:l]0 

18 

89  67—90    4 

90    0  20 

90    0   0 

rw=100:OT 

18 

87  54—88    9 

88    2    0 

88    010 

Ajftercantiousmeltuig  under  acover  slip  on  a  microscopeslide,  iodoform 
erystallisee  readily,  giving  broad,  individual  crystal  flakes,  the  surfaces 
of  which  are  parallel  to  e  {111} ;  the  optic  axis  of  negative  double  re- 
fraction emerges  normally  to  the  film  surface. 

li  is  interesting  to  note  that  a  large  proportion  of  compounds  of 
simple  oonstitution  crystallise  in  systems  of  high  symmetry,  such  as 
the  cubic  or  hexagonal.  It  may  also  be  remarked  that,  whilst  the 
molecule  of  carbon  tetriodide  has  partial  cubic  symmetry  and  crystaf- 
lises  in  the  cubic  system,  the  molecule  of  iodoform  has  partial  hexagonal 

Digitized  by  VjOOQ IC 


48  PEBKIN  AND  THOBPE:  /8/3-DIMETHTLQLT7TAIUC 

symmetry  and  crystaUises  in  the  hexagonal  system.  Many  other 
similar  analogies  could  be  quoted,  and  although  complications  due  to 
polymorphism  frequently  occur,  it  may  be  stated  that  a  knowledge  of 
the  chemical  constitutions  of  simple  compounds  often  allows  of  a  safe 
prognosis  of  the  crystalline  form  which  those  compounds  assume. 

Ghbmioal  Depabtmknt, 

CsMTaAL  Tbohnioal  College,  London. 


VI. — fifi'Dimethylglutaric  Acid  and  its  Derivatives; 
Synthesis  of  cis-  and  trans- C7aronic  Adds. 

By  William  H.  Perkin,  jun.,  and  Jocbltn  F.  Thorpe. 

Cabonb,  OioHj^jO,  one  of  the  most  important  ring  ketones  in  the 
terpene  series,  is  formed  when  dihydrocarvone  hydrobromide  is  treated 
with  alcoholic  potash,  hydrogen  bromide  being  eliminated,  a  decompo- 
sition which,  according  to  G.  Wagner,*  may  be  formulated  in  the 
following  manner. 

CH-CHj       •  CH-CHg 


H2C      CO  / 

I       I  HjO  CO 

HjC      CH2  =  I  (CHg),  I  +      HBr. 

Sy  HjC      C CH 

(CH3)26Br  \^^ 

Dihydrocanrone  hydrobromide.  Carone. 

This  view  of  the  constitution  of  carone  was  considered  probable  by 
Baeyer,  who,  in  order  to  confirm  this  formula,  carried  out  a  number 
of  important  experiments  on  carone,  during  the  course  of  which  he, 
in  conjunction  with  Ipatieff,  investigated  the  behaviour  of  this  sub- 
stance on  oxidation  with  permanganate  {Bw.,  1896,  29,  2796). 
It  was  found  that,  although  carone  is  very  stable  towards  perman- 
ganate  at  the  ordinary  temperature,  it  is  moderately  readily  oxidised 
at  100^,  with  formation  of  two  isomeric  dibasic  acids,  C5H3(COOH)2y 
melting  at  176^  and  212^,  which  were  named  caronic  acids.  Tlxe 
former  of  these,  which  is  produced  in  much  the  larger  quantity, 
readily  yielded  an  anhydride  melting  at  54 — 56°  when  boiled  with 
acetyl  chloride,  but  the  other  acid  was  not  affected  by  this  treatment. 

*  Compare  Baeyer  {Ber,,  1896,  29,  5  and  2796). 

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ACID  AND  ITS  DERIVATIVES.  49 

A  careful  examination  of  these  acids  led  Baeyer  and  Ipatieff  to  the 
conclusion  that  the  caronic  acids  were  stereoisomeric  modifications  of 
dimethyltrimethylenedicarboxylic  acid. 

0(CH3),  C(CH,), 

/  /\ 

COOH-C C-OOOH  H-C C-H, 

H  H  OOOH  COOH 

fndu-Cuoiiic  acid.  ei»-Cuoiiio  acid. 

and  that  these  were  formed  by  the  ozidstion  of  carone  at  the  points 
indicated  by  the  dotted  lines  in  the  formula 

CH-CHg 


H.C      C — CH 

\ 


CH 

That  these  acids  have  the  same  structure  and  are  stereoisomeric 
seemed  probable  from  their  behaviour  towards  hydrobromic  acid  at 
100^,  under  which  conditions  both  are  converted  into  terebic  acid  with 
disruption  of  the  trimethylene  ring  {loc.  cU,,  p.  2801). 


C(CH,), 
COOH-CH— CH-COOH  +  HBr  -  COOH- CH»-<!3H- COOH 


CO- 


Br9(CH3), 

2* 

'(^^8)2        +   HBr. 


•CHg- CH-COOH 

Ho  mention  is,  however,  made  of  any  attempt  to  convert  the  one 
modL€cation  into  the  other. 

In  studying  this  important  work,  it  seemed  to  us  that  it  would  be 
most  interesting  to  find  some  means  of  synthesising  the  caronic  acids, 
and  of  thus  placing  their  constitution  beyond  doubt.  This  was 
ultimately  accomplished  in  the  way  described  in  this  paper. 

Some  time  since,  it  was  shown  by  Goodwin  and  Ferkin  (Trans., 
1896,  60,  1476),  that  ethylic  dimethylaciylate  condenses  with  the 
sodium  derivative  of  ethylic  malonate  with  formation  of  ethylic 
dimethylpropanetricarboxylate, 

{OOOCJB^^)fin'  C(CH8)2'  CHj-  COOC2H5, 
and  from  this,  by  hydrolysis  and  elimination  of  carbon  dioxide,  )3^-di- 
methylglutaric  acid,  COOH- CH^- C(CH3)2- CH^*  COOH,  was  prepared. 
The  yield  of  acid  obtained  in  this  way  is  small,  but  by  substi- 
VOL.   LXXY  r^  T 

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50  PfiRKlK  AND  TltORPfe  :  /8/8-t)IMETHYLatUTARtC 

tilting  ethylic  cyaaacetate  for  ethylic  malonate  in  the  condensation 
with,  ethy lie  dimethylacrylate,  wenonrfind  that  the  yield  of  condensation 
product,  which  consists  of  a  mixture  of  some  ethylic  a-cyaruhfiP-difrntkyl- 
glutarate,  COOCgHj-  CH(CN)-C(CHg)j-  CHg-  COOCgHg,  with  much  of  the 
hydrogen  ethylic  salt,  COOH-CH(CN)-C(CHs)2-CHj-COOC2H6'  " 
more  than  80  per  cent,  of  the  theoretical,  and,  as  these  ethereal 
salts,  on  boiling  with  50  per  cent,  sulphuric  acid,  are  quantitatively 
converted  into  ^^-dimethylglutaric  acid,  it  is  now  an  easy  matter  to 
prepare  this  acid  in  quantity. 

When  the  anhydride  of  dimethylglataric  acid  is  treated  with  phos- 
phorus pentabromide  and  bromine, and  the  product  poured  into  absolute 
alcohol,  eifiylic  bramodimethylgltUawate, 

COOCaHg-  CHBr  •  C(CH3)2-CH2-  COOCgH^, 
is  produced,  together  with  large  quantities  of  the  hydrogen  ethylic 
salt  of  the  same  acid,  COOH- CHBr •C(CH3)2-CH2-COOC2H5 ;  that  the 
latter  should  be  produced  in  such  quantities  is  certainly  remarkable, 
and  a  possible  explanation  of  its  formation  is  given  in  the  experi- 
mental part  of  this  paper.  When  ethylic  bromodimethylglutarate  is 
digested  with  alcoholic  potash,  hydrolysis  and  elimination  of  hydrogen 
bromide  takes  place  simultaneously,  and  a  mixture  of  acids  is  ob- 
tained which,  by  conversion  into  the  ammonium  salts  and  treatment 
with  alcohol,  as  recommended  by  Baeyer  and  Ipatieff  {loc,  dt,,  2978), 
is  easily  separated,  and  found  to  consist  of  large  quantities  of  trans- 
ca/ronic  addj  some  lactone  acid  of  hydroxydimethylglutaric  acid  (see 
below),  and  traces  of  cis-caromc  acid. 

This  synthesis  of  the  caronic  acids  may  be  represented  in  the 
following  way. 

C(CH3),  C(CH,), 

/       \  gives  /\ 

COOC^,-CHBr    CH,- COOC^Hs  COOH- OH-CH- COOH. 

Hydrogen  ethylic  bromodimethylglutarate, 

COOH-CHBr-C(CH3)2-CH2-  OOOC2H5, 
on  treatment  with  alcoholic  potash,  is  quantitatively  converted  into 
^rotw-caronic  acid,  apparently  without  even  traces  of  the  cts-modifica- 
tion  being  formed.  The  synthesis  of  a  trimethylene  compound  in  the 
manner  represented  above  is  remarkable,  but  a  few  similar  cases  have 
been  observed,  as,  for  example,  in  the  formation  of  acetyltrimethylene 
by  the  action  of  alkalis  on  acetylpropyl  bromide, 

CHa'CO-CHg^^^  «     CH3-CO-CH<5^2  +  HBr. 

The  synthetical  caronic  acids  have  been  very  carefully  investigated, 
and  it  is  shown  in  the  experimental  part  of  this  paper  that  their  pro- 
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ACID  AND  ITS  DERIVATIVES.  51 

periiee  agree  in  all  respects  with  those  of  .the  acids  obtained  by  Baeyer 
and  Ipatieff  from  carone,  so  that  there  cannot  be  any  doubt  as  to  tha 
identity  of  the  acids  produced  by  these  different  methods. 

One  additional  point  of  interest  has  been  discovered,  namely,  that 
IratMHsaionic  acid  is  converted  into  the  anhydride  of  cM-caronic  add 
by  the  action  of  acetic  anhydride  at  220^,  a  transformation  of  the 
fiww-into  the  ctt-modification  which  was  required  to  clearly  show 
that  these  two  acids  are  stereoisomeric. 

Furthermore,  it  is  shown  in  this  paper  that  aqueous  sodium  car- 
bonate hydrolyses  the  hydrogen  ethylic  salt  of  bromodimethylglutaric 
acid,  CXX)H*  CRBt*0{OH^)2*  CH^*  COOO^H^,  in  a  manner  quite  different 
from  alcoholic  potash,  with  formation  of  the  IctoUme  of  a-hydroxy- 

talline  substance   which    melts  at  112*^  and  is  isomeric  with  the 
caronic  adds. 

When  ethylic  bromodimethylglutarate, 

0000^5-  CHBr-  C(CH8)j-  CHj-OOOOjHj, 
is  digested  with  diethylaniline,  hydrogen  bromide  and  ethylic  bromide 
are  eliminated  and  an  ethereal  salt  is  obtained,  which,  on  examination, 
has  been  found  to  consist  of  the  ethylic  salts  of  ^arM-caronic  add,  and 
of  the  laeUmiB  of  hydroxydimethylglutaric  acid. 


EXPEBIMBNTAL. 

CondenMion  of  Ethylic  JHmeihylacrylaie  toiih  tiie  Sodium  Derivative  qf 
Ethylic  CyanaceUOe. 

^)8.Dimethylglutario  acid,  OOOH-OHj-C(CH8)j-CH3-  COOH,  the  acid 
which  is  the  starting-point  in  the  synthesis  of  the  caronic  adds,  was 
fint  prepared  by  Goodwin  and  Ferkin  (Trans.,  1896,  69,  1475),  who 
obtained  it  by  the  following  series  of  reactions. 

Ethylic  dimethylaerylate  was^  in  the  first  place,  digested  with  the 
sodiom  derivative  of  ethyUo  malonate  in  alcoholic  solution,  when  con- 
densation took  place  with  formation  of  ethylic  dimethylpropanetri- 
Wtfboxylate, 

(00O0jH5)2OH2  +  (0H3)^0:CH-  COOCjHg  = 

(COOO,H^)jCH-  C(CH3)j-  CHa'COOOjH^. 

This  ethereal  salt,  on  hydrolysis,  yields  the  corresponding  tribasie 
add,  which,  at  200^,  loses  carbon  dioxide  with  formation  of  )3^-dimethyl- 
glataric  add,  OOOH*CH2-C(CH3)2-CHj-OOOH,  and  from  this  the 
anhydride  is  readily  prepared  by  treatment  with  acetic  anhydride. 
The  yield  of  the  original  triethylic  salt  is  unfortunately  not  good,  and 

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52  PERKIN  AND  THORPE  :  /8/9-DIMETHYLGLUTARIC 

seldom  reaches  more  than  40  per  cent,  of  the  theoretical ;  indeed,  the 
average  yield  is  scarcely  more  than  28  per  cent.  Until  quite  recently, 
*  we  have  prepared  all  the  dimethylglutaric  anhydride  required  for  this 
research  by  the  method  devised  by  Goodwin  and  Perkin.  A  few  months 
since,  however,  we  discovered  that  the  yield  may  be  very  greatly  im- 
proved by  substituting  ethylic  cyanacetate  for  ethylic  malonate  in  the 
condensation  with  ethylic  dimethylacrylate,  the  yield  of  condensation 
product  being  increased  to  at  least  80  per  cent,  by  this  means.* 
Ethylic  a-cyano-pp-dimethylgliUarcUe, 

COOCjHg-  CH(ON)-C(CH8)2-CH2-  COOCgHg, 
has  been  prepared  in  large  quantities   by  the  above  process,  the 
details  of  preparation  being  the  following.     Sodium  (23  grams)  is 
dissolved  in  alcohol   (300  grams),  the  solution  of  sodium  ethoxide 
mixed    with    ethylic    cyanacetate    (113    grams),    ethylic    dimethyl- 
acrylate  (129  grams)  is  then  added,  and  the  whole  heated  in  a  reflux 
apparatus  on  the  water  bath.    The  sodium  derivative  of  ethylic  cyano- 
acetate,  which  at  first  separates  as  a  white,  crystalline  powder,  slowly 
dissolves,  and  the  liquid  darkens  and  gradually  sets  to  an  almost  solid 
cake  of  the  sodium  derivative  of  the  condensation  product,  the  reaction 
being  finished  in  about  24  hours.    Water  is  now  added,  and  the  oily  con- 
densation product  extracted  with  ether  in  the  usual  way;  the  ethereal 
solution,  after  washing  with  water  and  drying  over  calcium  chloride, 
deposits  a  thick  oil  which,  after  two  distillations  under  reduced  pres- 
sure, passes  over  constantly  at  190°  (30  mm.),  and  consists  of  pure 
ethylic  cyanodimethylglutarate. 

0*2614  gave  13-5  c.c.  nitrogen  at  20"^  and  750  mm.     N  »  5*80. 
C12H19NO4  requires  N  =  5-81  per  cent. 

The  yield  of  this  substance  produced  in  the  above  reaction  is  about 
15  per  cent,  of  the  theoretical. 

The  principal  product  formed  in  this  condensation  is  the  acid  ethylic 
salt  of  the  substance  just  mentioned,  that  is,  ethylic  hydrogen  a-cyano-PP* 
difnethylghacuxae,  COOH-CH(CN)-C(OH3),-OHj-COOC2H5 ;   this    is 
obtained  on  acidifying  the  mother  liquors  of  the  condensation  product 
mentioned    above    and    extracting  with   ether.       After  thoroughly 
washing  the^ethereal  solution^  drying  over  calcium  chloride  and  evapo* 
rating  the  ether,  a  thick  oil  ib  left,  which  was  not  analysed,  since, 
for  reasons  stated  below,  it  cannot  be  purified  by  distillation,  and  it 
showed  no  signs  of  crystallising.     The  yield  of  this  substance  formed 
is  no  less  than  60 — 70  per  cent,  of  the  theoretical. 

*  This  immensely  increaaed  yield  is  not  confined  to  this  condensation,  since  i1 
h&a  been  found  that  a  similar  resalt  is  obtained  when  other  unsaturated  etherea] 
salts,  such  as  ethylic  crotonate,  ethylic  methylacrylate,  kc,  are  employed,  and  tb4 
products  formed  in  this  way  are  at  present  being  investigated  by  one  of  us. 


ACID  AND  ITS  DERIVATIVES.  63 

It  is  very  difficult  to  onderstaDd  why  this  acid  ethereal  salt  should 
be  produced  in  such  large  quantities ;  its  formation  is  certainly  not 
due  to  the  presence  of  water,  as  several  caref  al  experiments  which 
were  made  with  specially  dried  alcohol  gave,  in  every  case,  the  same 
yield. 

When  distilled  under  ordinary  pressures,  this  acid  ethereal  salt  is 
readily  decomposed,  with  elimination  of  carhon  dioxide  and  formation  of 
ea^  y-cyano-PP-dtmeihylbutyraU,  CN-CH5-C(CH8)3-CH2-COOC2H5, 
which  is  a  mobile  oil  distilling  without  decomposition  at  244°. 

0-2783  gave  21-8  c.c.  of  nitrogen  at  20°  and  735  mm.     N  =  8-66. 
CjjHjsOgN  requires  N  =  8'28  per  cent. 

When  digested  with  concentrated  hydrochloric  acid  in  a  reflux  appa- 
ratas,  it  rapidly  dissolved,  and  on  cooling  and  mixing  with  an  equal 
bulk  of  water,  a  mass  of  crystals  separated,  which,  on  examination, 
was  found  to  consist  of  the  imide  of  dimethylglutaric  acid. 


PP-Dimethylglutartmide,  {CK^)^0<!^\^^1!^R. 

This  substance  is  produced  by  the  hydrolysis  either  of  ethylic 
a*cyanodimethylglutarate  or  hydrogen  ethylic  cyanodimethylglutarate, 
the  process  in  the  two  cases  being  somewhat  differently  conducted. 
When  the  first  or  neutral  ethylic  salt  is  employed,  the  pure  substance 
(60  grams)  is  heated  with  methyl  alcoholic  potash  (50  grams)  for 
2  hours,  the  solution  evaporated  until  free  from  alcohol,  acidified,  and 
extracted  with  ether.  After  evaporating  the  ether,  the  residue,  which 
probably  consists  principally  of  cyanodimethylglutaric  acid,  is  digested 
in  a  reflux  apparatus  with  concentrated  hydrochloric  acid  for  3  hours, 
when,  on  evaporating,  the  whole  becomes  filled  with  colourless  needles 
of  the  imide ;  these  are  collected  with  the  aid  of  the  pump  and  recrys- 
tallised  from  water.  In  the  case  of  the  hydrogen  ethylic  salt,  it  is 
only  necessary  to  boil  with  an  equal  volume  of  concentrated  hydro- 
chloric acid  for  3  hours,  in  order  to  get  directly  an  almost  quantita- 
tive yield  of  the  imide,  care  being  taken  to  so  moderate  the  reaction 
as  to  avoid  loss  from  the  evolution  of  carbonic  anhydride,  which  is  apt 
to  become  very  vigorous. 

A^Dimethylglutarimide  crystallises  from  water  in  long,  colourless 
needles,  which  melt  at  144°,  and  at  a  higher  temperature  distil 
unchanged.  It  is  very  sparingly  soluble  in  cold  water,  readily  in  hot 
water,  and  is  almost  insoluble  in  dry  ether. 

0*3034  gave  26  c.c.  nitrogen  at  17°  and  750  mm.    N  =  9  *82. 
CyH^jNO^  requires  N  «  9*93  per  cent. 


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54  PERK  IN  AND  THORPE:   /8/9-DIMETHTLGLUTARIC 

This  imide  is  quantitativelj  converted  into  )3)3-dimethylglataric 
acid  (m.  p.  101^)  on  heating  in  a  dosed  tube  with  concentrated 
hydrochloric  acid  for  5  hours  at  200^  or  by  heating  with  dilute 
sulphuric  acid  (50  per  cent.)  for  3  hours  on  a  sand  bath,  the  acid 
being  readily  obtained  from  the  products  of  hydrolysis  by  extraction 
with  ether  in  the  usual  way. 

Pp-DiTnethylghdaric  Anhydride,  V^^*  ^(CHg)^-  CH2 

This  anhydride  has  already  been  obtained  from  the  acid  by  treatment 
with  acetic  anhydride  (Trans.;  1896, 69, 1475),  but  the  process  used  in 
the  production  of  the  acid  and  conversion  of  this  into  the  anhydride  has 
subsequently  been  much  improved,  and  very  large  quantities  have 
been  prepared  for  the  purposes  of  this  research  by  the  following 
method.  Ethylic  cyanodimethylglutarate,  as  well  as  the  acid  ethylic 
salt,  which  is  always  the  chief  product  in  the  condensation  of  ethylic 
cyanoacetate  with  ethylic  dimethylacrylate,  are  boiled  with  an  equal 
volume  of  50  per  cent,  sulphuric  acid  for  12  hours  on  the  sand  bath. 
The  exact  end  point  of  the  reaction  is  difficult  to  determine,  owing  to  the 
fact  that  the  sulphuric  acid  converts  a  large  proportion  of  the  dimethyl- 
glutaric  acid  into  anhydride,  and  this,'  like  the  unhydrolysed  ethylic 
salts,  floats  on  the  surface  of  the  aqueous  liquid  as  on  oil ;  we  found, 
however,  that  12  hours  was  sufficient  to  ensure  complete  hydrolysis. 

The  product,  when  cold,  is  extracted  several  times  with  ether,  the 
ether  distilled  off,  and  the  residue,  without  further  purification,  mixed 
in  the  same  flask  with  an  equal  bulk  of  acetic  anhydride,  and  boiled 
for  3  hours  on  a  sand  bath,  using  a  reflux  condenser.  After  distilling 
off  most  of  the  acetic  anhydride  under  the  ordinary  pressure,  the 
crude  dimethylglutaric  anhydride  which  remains  is  purified  hy 
fractionation  under  reduced  pressure,  when  almost  the  whole  passes 
over  at  181^  (25  mm.)  as  a  colourless  oil,  which,  on  cooling,  solidifies  to 
a  hard,  crystalline  cake. 

The  yield  of  pure  anhydride  obtained  in  this  way  was  over  90  per 
cent,  of  theory  calculated  from  the  ethylic  cyanodimethylglutarate,  or 
about  73  per  cent,  calculated  from  the  ethylic  cyanoacetate  originally 
used  in  the  condensation. 

Actum  qf  Bromine  on  DimetJiylglutaHc  Anhydride, — In  investigating 
this  reaction,  dimethylglutaric  anhydride  was  treated  with  phosphorus 
pentabromide  and  bromine,  and  the  bromo-  or  dibromo-acid  bromides 
thus  produced  were  converted  into  methylic  or  ethylic  salts  by  the 
action  of  methylic  or  ethylic  alcohols. 

EHhylie  a-bromo-fifi-dimethylgluiaraie, 

COOCgH^-  CHBr  •C(CH3)j-  QH^*  COOCaH^, 

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ACID  AND  ITS  DERIVATIVES.  55 

was  prepared  from  dimethylglutaric  anhydride  (13  grams)  by  mixing 
it  with  phosphorus  pentabromide  (50  grams),  and  heating  the  mizture 
in  a  refloz  apparatus  on  the  water  bath  until  the  reaction  was  com- 
plete ;  bromine  (16  grams)  was  then  gradually  added,  and  as  soon  as 
the  vigorons  evolution  of  hydrogen  bromide  had  ceased  the  whole  was 
heated  on  the  water  bath  until  colourless,  and  the  product  poured  into 
well-cooled  absolute  alcohol.     After  being  allowed  to  stand  for  some 
hours,  water  was  added,  when  a  heavy  oil  was  precipitated  which  was 
extracted  with  ether,  and  the  ethereal  solution,  after  washing  well 
with  sodium  carbonate  solution,  was  dried  over  calcium  chloride  and 
evaporated.  The  nearly  colourless  heavy  oil  thus  obtained,  on  fractiona- 
tion, distilled  constantly  at  181°  (20  mm.),  and  consisted  of  pure  ethylic 
bromodimethylglutarate. 


01820  gave  00669  AgBr.     Br  =  27-23. 
CuHjjBrO^  requires  Br  =  27' 


27*11  percent. 

Hydrogen  Ethylic  Salt  of  a-BroTno-PfidimcthylgluUbrie  Acid, 
COOH-  CHBr-C(CH8)2-  CHg-  OOOC2H5. 

This  is  precipitated  in  considerable  quantity  when  hydrochloric 
acid  is  added  to  the  sodium  carbonate  washings  obtained  as  ex- 
plained in  the  last  paragraph.  It  is  a  heavy,  colourless  oil  which 
distils  without  decomposition  at  240"^  (35  mm.). 

01932  gave  0*0771  AgBr.    Br  «  29*80. 

CgH^sBrO^  requires  Br  =  29-97  percent. 

The  formation  of  this  acid  ethylic  salt  in  the  proportion  of  about 
20  per  cent,  of  the  total  product  of  bromination  is  not  due  to  the 
presence  of  water  in  the  alcohol  used,  as  is  shown  by  the  fact  that 
exactly  the  same  amount  was  formed  in  an  experiment  in  which  extra 
precautions  were  taken  to  eliminate,  as  far  as  possible,  every  trace  of 
water.  It  seems  to  us  probable  that,  from  the  examination  of  a 
number  of  similar  cases,  some  acid  bromides  have  the  power  of  decom- 
posing alcohol  in  such  a  way  as  to  form  tha  free  acid  and  ethylic 
bromide,  thus  :  R-COBr  +  HO-CjjHg  =  R-COOH  +  CgH^Br. 

It  is  also  possible  that  the  position  of  the  bromine  atom  may 
scoount  for  the  difficulty  with  which  this  hydrogen  ethylic  salt  is 
further  etherified,  as  an  experiment  which  we  made  with  the  object  of 
converting  the  hydrogen  ethylic  salt  into  the  neutral  ethereal  salt,  by 
means  of  alcohol  and  hydrogen  chloride,  showed  that  very  little 
etherification  had  taken  place. 

Methylie  a-broma-fipdimetkylglutarate, 

COOCH3-CHBr-C(CH3)2-CH2-  COOCH3, 
8  obtained  when  the  hromo-acid  bromide  of  dimethylglutaric  acid, 

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56  PEBKIN  AND  THORPE:  /8/8-DIMETHTLGLUTARIC 

prepared  as  explained  above^  is  poured  into  well  cooled  methylio 
alqphol.     It  is  a  mobile  liquid  boiling  at  172°  (20  mm.). 

Lactone  of  a-ffydroxy-PP-dimethylglutaric  Acid, 


•CH-C(0H3VCH, 


This  interesting  substance,  which  is  isomeric  with  the  caronic  acids, 
was  prepared  as  follows. 

The  hydrogen  ethylic  salt  of  bromodimethjlglutaric  acid  (20  grams) 
was  dissolved  in  dilute  sodium  carbonate  and  boiled  in  a  reflux 
apparatus  on  a  sand  bath,  care  being  taken  that  the  solution  always 
had  a  distinctly  alkaline  reaction.  As  soon  as  a  small  quantity  of 
the  liquid  gave  no  precipitate  with  hydrochloric  acid,  the  whole  was 
acidified,  saturated  with  ammonium  sulphate,  and  repeatedly  extracted 
with  ether  ;  the  dried  ethereal  solution,  when  evaporated,  gave  a  hard, 
crystalline  mass  which,  on  being  left  in  contact  with  porous  porcelain 
for  some  days,  became  quite  colourless  and  melted  at  80 — 100^.  In 
order  to  purify  this  crude  product,  and  especially  with  the  object  of 
determining  whether  it  contained  any  trana-caxonic  acid  (p.  59),  the 
lactone  was  dissolved  in  a  slight  excess  of  ammonia,  evaporated  on 
the  water  bath,  and  the  well  dried  ammonium  salt  warmed  with 
absolute  alcohol,  when  the  whole  dissolved  readily,  showing  that  no 
trana-oaxomo  acid  was  present.  Ether  was  then  added  to  the  alcoholic 
solution  until  a  slight  turbidity  was  produced,  and  the  fine,  transparent 
prisms  of  the  pure  ammonium  salt  deposited  on  standing  were 
coUectr  i,  washed,  and  converted  into  the  acid,  which  was  further 
purified  by  repeated  recrystallisation  first  from  benzene  and  then  from 
water.     Analysis. 

01643  gave  03225  CO,  and  00932  HjO.    0  =  5353 ;  H - 6-30. 
CyHi^jO^  requires  C  =  53-16  ;  H  =  6-33  per  cent. 

This  lactone  melts  at  112°,  and  when  heated  in  a  small  retort 
distils  without  change.  It  is  readily  soluble  in  ether,  acetone,  ethylic 
acetate,  and  hot  benzene,  moderately  in  chloroform,  and  almost 
insoluble  in  light  petroleum. 

Action  qf  Alcoholic  PoUuh  on  Ethylic  a-Bromo-PP-dimethylgluUiraU. 
FomuUion  qf  cis-  and  trans-(7aronio  Acids, 

C(CH3), 

COOH-  CH— CH-  COOH. 

In  this  interesting  experiment,  the  brom-ethereal  salt  (15  grams) 
was  digested  in  alcoholic  solution  with  caustic  potash  (15  grams)  for 

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ACID  AND  ITS  DERIVATIVES.  57 

10  hours,  and  the  product,  after  being  freed  from  alcohol  bj  cTapora- 
tion  on  tbe  water  bath  with  the  addition  of  water,  was  diflsolyed  in 
^ater,  acidified,  and  extracted  sereral  times  with  ether.  On  distilling 
off  the  ether,  a  syrupy  mass  was  obtained,  which  became  partially 
solid  on  standing  ;  this  was  dissolved  in  a  little  water  and  saturated 
with  hydrogen  chloride,  when  the  crystalline  solid,  which  slowly 
separated  after  being  collected  and  dried  on  a  porous  plate,  melted 
indefinitely  between  170°  and  200°.  This  crude  substance  was  dis- 
solved in  ammonia,  evaporated  to  dryness,  and  the  residual  solid 
ammonium  salt  ground  up  with  cold  absolute  alcohol;  a  small 
quantity  passed  into  solution,  but  most  of  it  remained  undissolved.* 
The  insoluble  salt  was  collected,  washed  with  absolute  alcohol, 
dissolved  in  a  little  water,  acidified  and  extracted  with  ether ;  the 
ethereal  solution,  on  evaporating,  deposited  a  solid  acid  which  even 
before  recrystallising  melted  at  210—212°,  and  after  recrystallising 
from  water  at  213°.'  This  substance  is  trans-ooronte  octi.  The 
alcoholic  filtrate  from  the  insoluble  ammonium  salt  of  ^a9M-caronic 
add,  on  being  mixed  with  ether  and  allowed  to  stand,  deposited  a 
small  quantity  of  crystalline  solid ;  this,  after  collecting,  acidifying,  and 
extracting  with  ether,  yielded  an  acid  melting  at  176°,  which,  doubt- 
less,  consisted  of  cif-<»^ronic  acid  (m.  p.  176°),  but  the  quantity  was 
too  small  for  analysis.  In  this  hydrolysis,  therefore,  both  the 
caronic  adds  appear  to  be  formed,  but  the  ^an««modification  in  far 
larger  quantity  than  the  et9-modification. 

On  evaporating  the  solution  after  the  precipitation  of  the  cis-  and 
trwu-caxomc  acids  to  dryness  with  ammonia,  and  dissolving  the 
residne  in  alcohol,  an  oily  ammonium  salt  was  precipitated  on  the 
addition  of  much  ether,  which,  on  long  standing,  became  solid  ;  from 
this,  on  acidifying,  a  considerable  quantity  of  the  lactone  of  hydroxy- 
dimethylglutaric  acid  was  obtained,  melting  at  112°. 

Aeiwn  of  Pciaah  en  Oe  Hydrogen  Bthylie  Salt  qf  a-Bromo-fifi-dimethyl- 

gkUarie  Acid, 

This  hydrolysis,  which  gives  by  far  the  best  yield  of  tron^-caronic 
acid,  was  conducted  as  follows.  Equal  weights  of  the  brom-ethereal 
salt  and  caustic  potash  were  heated  together  in  alcoholic  solution  in  a 
reflux  apparatus  for  3  hours,  and  after  evaporating  the  alcohol, 
acidifying,  and  extracting  with  ether,  exactly  as  explained  in  the  last 
experiment,  a  hard,  solid,  crystalline  cake  was  obtained ;  this,  on 
being  crystallised  once  from  water,  melted  at  213°,  and  consisted  of 
pure  <r0tw^»ronic  acid.     On  treating  this  acid  and  its  mother  liquors 

*  This  nit  is  the  acid  ammoniam  salt  of  traTU-cawnic  acid,  and  has  the  formula 
C»H],K04  (Baeyer,  Ser„  1896,  29,  2800). 

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58  PERKIN   AND   THORPE:  /S/S-DIMBTHYLGLUTARIC 

with  ammonia  and  alcohol,  as  explained  above,  we  were  not  able  to 
extract  even  traces  of  the  cif-modifioation  or  of  the  lactone  of 
hjdroxydimethylglutaric  acid. 

It  is  remarkable  that  hydrogen  ethylic  bromodimethylglutarate 
should  behave  so  differently  from  the  normal  ethy lie  salt  on  treatment 
with  potash  under  the  same  conditions,  and  that  in  the  latter  case, 
besides  ^anf-caronic  acid  and  traces  of  the  ct9-modification,  such  con- 
siderable quantities  of  the  lactone  of  hydroxydimethylglutaric  acid 
should  be  produced. 

The  formation  of  ^roTW-caronic  acid  from  the  hydrogen  ethylic  salt 
seems  to  us  to  prove  that  this  salt  has  the  formula 

COOH-  CHBr-C(CH3)j«  OHg-  COOC3H5. 
given  to  it  on  p.  50,  and  that  elimination  of  hydrogen  bromide  takes 
place  before  hydrolysis.  If  this  ethereal  salt  had  the  alternative 
formula,  C00C2Hj-CHBr-C(C  0^3)2' CH2- COOH,  the  elimination  of 
hydrogen  bromide  would  be  expected  to  take  place  between  the 
bromine  atom  and  the  hydrogen  atom  of  the  carboxyl  group,  and  the 
lactone  of  hydroxydimethylglutaric  acid  would  be  formed ;  this, 
however,  is  not  the  case. 

Action  of  Dietkylanilvne  on  Ethylic  Bromodimethylglutarate, — As  it 
has  frequently  been  found  that  diethylaniline  is  a  very  valuable 
reagent  for  removing  hydrogen  bromide  from  organic  substances, 
it  was  thought  that  interesting  results  might  be  obtained  if  its 
behaviour  were  investigated  in  the  present  instance.  Accordingly, 
50  grams  of  ethylic  bromodimethylglutarate  was  boiled  in  a  reflux 
apparatus  with  75  grams  of  pure  diethylaniline  for  2  hours,  and  after 
cooling,  the  nearly  solid  product  was  treated  with  dilute  hydrochloric 
acid,  and  the  oil  which  separated  extracted  with  ether.  The  ethereal 
solution  was  dried,  evaporated,  and  the  residual  oil  fractionated  a 
great  many  times,  first  under  reduced  and  then  under  the  ordinary 
pressure.  It  was  thus  separated  into  two  fractions  which  boiled  at 
241°  and  at  about  265—275°  " 

The  oil  boiling  at  241°,  on  analysis,  gave  the  following  numbers. 

0-1345  gave  0*3032  COj  and  0-1087  H^O.     C  =  61-48 ;  H  =  8-98. 
CijFjgO^  requires  0  =  61-68;  H»8-41  per  cent. 

Since  this  oil,  on  hydrolysis,  yielded  (ran«-caronic  acid,  it  is  evidently 
the  ethereal  salt  of  this  acid. 

The  fraction  265 — 275°,  which  was  not  analysed,  gave,  on  hydrolysis, 
the  lactone  of  hydroxydimethylglutaric  acid,  and  is  evidently  the 
ethereal  salt  of  this  lactonic  acid.  These  two  substances  were  ob- 
tained in  about  equal  quantities. 


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ACID  AND  ITS  DERIVATIVES.  69 

tnnBrCaronic  acid,  COOH-(^ — (J3-C00H. 

H      H 

The  synthetical  acid  has  properties  identical  with  those  described 
by  Baeyer  and  Yiiliger  {Ber.,  1896,  29,  2800)  as  characteristic  for 
the  add  from  carone.  It  is  sparingly  soluble  in  cold  water,  but 
readily  in  hot  water,  and  separates  from  its  hot  solution  in  prisms 
which  melt  at  213^.  It  is  very  sparingly  soluble  in  ether,  ben^ne, 
and  cold  water,  and  almost  insoluble  in  chloroform  and  light  petroleum. 

01504  gave  0-2913  COg  and  00888  HgO.     0  =  62-82 ;  H  =- 666. 
CyHio04  requires  C  »  6316 ;  H  «  6'33  per  cent. 

The  gilver  saU  is  precipitated  as  a  white,  crystalline  powder  when 
silver  nitrate  is  added  to  a  neutral  solution  of  the  ammonium  salt. 

0-2660gave0-2177  OO2,00547H2Oand01638  Ag.  C  =  22-33;  H  =  229 ; 
Ag- 67-82. 
CyHgO^Aga  requires  C=*  22-57  ;  H=«2-15  ;  Ag  =  58-06  per  cent. 

<raii»>Caronic  acid  does  not  give  an  anhydride  when  digested  with 
acetic  anhydride,  but  when  heated  with  acetic  anhydride  at  220°  it 
yields  the  anhydride  of  ei»«aronic  acid  (p.  61).  That  it  is  a  saturated 
add  is  shown  by  the  fact  that  its  solution  in  sodium  carbonate  does 
not  reduce  permanganate. 

Conversion  of  trans-(7aronic  Acid  into  Terebic  Acid, 


I 


O-CHa-CH-COOH* 

It  was  stated  in  the  introduction  to  this  paper  that  one  of  the  most 
remarkable  reactions  of  trans-  and  cis-caronic  acid  discovered  by 
Baeyer,  was  the  transformation  of  these  acids  into  terebic  add  by  the 
action  of  hydrobromic  acid  at  100%  and  it  was  consequently  of  im- 
portance to  show  that  the  synthetical  acids  behaved  in  the  same 
manner  under  the  same  conditions. 

About  0'6  gram  of  pure  synthetical  irans-cajconio  add  was  heated 

with  about  5  cc.  of  concentrated  hydrobromic  acid  (saturated  at  0°) 

for  5  hours  at  100^;  the  hydrobromic  acid  was  then  removed  by 

evaporation^  on  the  water-bath,  and  the  residue  recrystallised^^  from 

water ;  the  colourless,  cubic  crystals  melting  at  174°  thus  obtained  gave 

the  following  numbers  on  analysis. 

0-U22  gave  02757  COj  and  0-0802  HgO.     C  =  5287  ;  H  =  6-26. 
C-jHj^O^  requires  C  «  6316  ;  H  =  6-33  per  cent. 

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60  /8/8-DIMETHYLGLUTARIC  ACID  AND  ITS  DERIVATIVES. 

Terebic  acid  has  the  same  empirical  formula  and  the  same  melting 
point  as  ct9-caronic  acid,  but  in  other  respects  these  acids  possess  very 
different  properties,  and  there  can  be  no  doubt  that  the  acid  obtained 
in  the  above  experiment  was  terebic  add,  and  not  unchanged  cU- 
caronic  acid,  for  the  following  reasons  (compare  Baeyer,  Bw,,  1896, 
29,  2799).  This  acid  yields  an  ammonium  salt  which  differs  from  the 
ammonium  salt  of  <»!8^oaronic  acid  in  that,  besides  having  a  different 
crystalline  form,  its  solution  in  alcohol  is  not  precipitated  by  ether. 
It  gives,  with  silver  oxide,  a  silver  salt  which  is  readily  'soluble  in 
water  and  crystallises  in  needles,  and  on  boiling  with^  baryta  water 
it  yields  the  characteristic  crystalline  barium  salt  of  diaterebic  acid. 
Finally,  a  small  quantity  heated  in  a  test  tube  gave  the  odour  of 
pyroterebio  acid, 

?^;?H.^H  -  cooh.ch,.ch:c(ch3),+co, 

and  the  residue,  dissolved  in  soda,  instantly  reduced  permanganate,  a 
behaviour  not  shown  by  ci8-caronic]acid,  which,  under  these  conditions, 
is  simply  converted  into  its  anhydrida 

Conversion  qf  trMiB'Caronio  Acid  into  ciB-Caronic  Acid. 

This  conversion,  which  had  not  previously  been  observed,  may  be 
readily  accomplished  in  the  following  way.  ^an«-Caronic  acid  is  mixed 
with  three  times  its  weight  of  freshly  distilled  acetic  anhydride,  and  the 
mixture  heated  in  a  sealed  tube  for  6  hours  at  220^.  The  dark  brown 
'product  is  then  freed  from  the  excess  of  acetic  anhydride  by  distillation, 
the  residue  dissolved  in  boiling  water,  digested  with  animal  charcoal, 
filtered,  and  evaporated  to  a  small  bulk ;  on  cooling,  large,  glistening, 
colourless  crystals  separate,  which  melt  at  1 76^,  and  consist  of  pure 
cig-caronic  acid. 

0-1602  gave  0-3108  CO,  and  00900  HjO.     0  =  52*91  ;  H  =  6-24. 
CyHjoO^  requires  0  =  63-16  ;  H  =  6-33  per  cent. 

cis-Coronio  cusid^   HC OH       ,  is  very  sparingly  soluble  in 

OOOH  COOH 
cold  water^  but  readily  in  hot  water,  and  crystallises  from  water 
most  beautifully  in  brilliant,  glistening  plates  with  bevelled  edges. 
It  is  sparingly  soluble  in  dry  ether  and  in  light  petroleum,  and  practi- 
cally insoluble  in  chloroform ;  it  dissolves  readily  in  sodium  carbonate, 
and  this  solution  does  not  decolorise  permanganate.  When  heated 
above  its  melting  point,  ot9-caronic  acid  is  rapidly  converted  into  its 


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STNTHBSIS  OF  a/3)3-TRIMETHTLGLnTARIC   ACID.  61 

anhydride.  The  ammonium  salt  of  cM-caronic  add  is  readily  obtained 
by  dissolving  the  acid  in  excess  of  aqueous  ammonia  and  evaporating 
the  solution  on  a  water  bath.  The  crystalline  residue  differs  most 
sharply  from  the  ammonium  salt  of  the  tram^&cLd  in  being  readily 
soluble  in  absolute  alcohol ;  from  its  alcoholic  solution,  it  is  precipitated 
by  ether  in  the  form  of  slender  needles.  When  cw-caronic  acid  is 
heated  with  hydrobromic  acid,  under  the  conditions  given  in  detail  in 
the  CQrresponding  experiment  with  the  ^raTi^acid  (p.  59),  it  is  con- 
verted into  ierebie  add  melting  at  174^. 

It  will  be  seen  from  this  short  description  of  the  properties  of  ctB- 
caronic  acid  that  the  synthetical  acid  is  identical  with  the  acid  obtained 
by  Baeyer  (loe.  cU.)  from  carone. 

C(CH,), 


Anhydride  of  cis-Caronic  add,  HC — CH. — ^This  anhydride  is 

dx)— O— CO 

foimed  either  when  ci^-caronic  acid  is  distilled,  or  when  trcms-caxonic 
acid  is  heated  at  220^  with  acetic  anhydride,  but  it  is  best  prepared 
by  boiling  ct»-caronic  acid  with  acetyl  chloride  until  hydrochloric  acid 
ceases  to  be  evolved,  evaporating,  and  crystallising  the  residue  from 
dry  ether,  wben  lustrous  plates  are  obtained  which  melt  at  56^. 

There  caim  be  no  doubt  that  this  is  the  anhydride  of  the  cM-acid, 
because  it  is,  as  Baeyer  found  {loe.  cit,,  p.  2799),  quantitatively  con- 
verted into  the  acid  on  boiling  with  water. 

The  authors  wish  to  state  that  this  research  was  carried  out  with  the 
aid  of  a  grant  from  the  Royal  Society  Eesearch  Fund,  and  that  they 
are  indebted  to  Mr.  E.  H.  Lees  for  making  most  of  the  analyses  given 
in  this  and  the  succeeding  communication. 

Chmis  CoLLsoE, 
Manchbstes. 


VIL — Synthesis  of  afiB'Trimethylglutaric  Add. 
COOH-  CH(OH3)-C(CHj^8-  CHg-  COOH. 

By  W.  H.  PsBKiK,  jun.,  and  Jooelyn  P.  Thobpb. 

Or  the  four  theoretically  possible  trimethylglutario  acids,  two  only, 
up  to  the  present,  have  been  prepared  synthetically,  namely,  the  aooi- 
add,  COOH-C(CH3)j,-CHj-CH(0H8)-0OOH,  by  Auwers  and  Victor 
Meyer  {Ber.,  1890,  ^,  293)  from  ethylio  a-bromisobutyrate  and  ''  mole- 
cular "  silver,  and  the  aa)8-acid,  COOH-  C(0H8)2-  CH(0H8)-0Hj-  COOH, 

Digitized  by  VjOOQIC 


62  pI:r^in  and  TfiOBPE:  synthesis  of 

which  was  prepared  by  us  (Trans.,  1897,  71,  1187),  by  the  reduction 
of  the  corresponding  trimethylglutaconic  acid, 

COOH-  C(CH3)2-  C(CH3):CH-  COOH. 
The  remaining  two  acids  are 

app COOH*  OH(CH3)-C(CH8)2-  CH,-  COOH,  and 

apay^ COOH-  CH(CH3)-CH(CH3)-CH(CH3)-COOH. 

Of  these,  the  first  has  a  special  interest,  for  the  following  reason. 

By  the  oxidation  of  camphoric  acid  with  permanganate  at  the  ordi- 
nary temperature,  Balbiano  {Ber.,  1894,  27,  2133  ;  1897,  30,  1908), 
obtained  an  acid  of  the  formula  C^H^j^s*  ^  which  he  assigned  the 
constitution 

COOH-  C(CH3)-  C(CH3)3-  CH-  COOH. 

I O ! 

This  acid,  on  reduction,  yielded  a  lactonic  acid  of  the  probable 
formula 

CH(CH3)-C(CH3)8-  CH-  COOH, 

and  this,  by  further  reduction  with  hydriodio  acid,  was  converted  into 
an  acid,  CgH^^O^,  which  Balbiano  considered  to  be  a^;3-trimetbyl- 
glutaric  acid,  because,  on  oxidation,  it  yielded  oa-dimethylsuccinic 
acid. 

Assuming  that  this  acid  is  aj9)3-trimethylglutaric  acid,  its  formation 
from  camphoric  acid  is  important,  as  affording  evidence  that  the  latter 
contains  the  group  C-C(CH3).C(CH3)2-C'C,  a  conclusion  which,  to- 
gether with  results  obtained  from  the  great  amount  of  work  which  has 
been  done  on  camphoronic  acid,  throws  much  light  on  the  constitution 
of  camphoric  acid  (compare  Trans.,  1898,  73,  797). 

It  thus  became  an  important  matter  to  be  certain  that  the 
formula  Balbiano  assigned  to  his  acid  is  correct,  and  for  this  reason 
we  have,  ever  since  the  publication  of  his  paper,  been  endeavouring  to 
synthesise  ay3)9-trimethylglutaric  acid,  and  it  is  only  quite  lately  that 
we  have  been  able  to  accomplish  this. 

In  the  first  place,  we  found,  as  the  result  of  a  great  many  experi- 
ments, that  it  seems  to  be  impossible  to  introduce  a  methyl  group 
into  ethylic  dimethylpropanetricarboxylate, 

(COOC,H5)2CH-  C(CH3)j-  CHj-  COOCgH^, 

at  the  point  marked  *,  by  the  action  of  sodium  ethoxide  and  methylic 
iodide.  Arguing  from  analogy  to  other  mono-substitution  products  of 
ethylic  malonate,  this  experiment  should  have  yielded  an  ethereal  salt 
which  would  have  given  ay3)3-trimethylglutaric  acid  on  hydrolysis 

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a^y6f-TRIMETHYLGLUTARiC  ACID.  63 

and  elimination  o!  carbon  dioxide,  but>  although  tried  under  very 
varied  conditions,  no  trace  of  this  acid  was  obtained. 

It  was  then  thought  possible  that  the  ethylic  trimethylpropanetri- 
carboxylate,  (COOC2H5)2C(CH3)-C(CH3)2-  CHg-  GOOC2H5,  which  should 
have  resulted  from  the  above  experiment,  might  be  formed  by  the 
condensation  of  ethylic  dimethylacrylate  with  the  sodium  derivative 
of  ethylic  mebhylmalonate,  bub  the  experiments  made  in  this  direction 
did  not  yield  a  trace  of  the  desired  compound,  and  many  other  syn- 
theses, which  need  not  be  mentioned  here,  also  gave  negative  results. 
Ultimately,  we  discovered  the  following  synthesis,  which  is  so  easily 
carried  out  that  large  quantities  of  aySyS-trimethylglutaric  acid  can 
now  be  obtained  in  a  short  space  of  time. 

The  method  consists  in  heating  together  ethylic  dimethylacrylate 
and  the  sodium  derivative  of  ethylic  cyanaoetate  in  alcoholic  solution 
until  the  condensation  to  the  sodium  derivative  of  etfiylic  eyanodi- 
meihylgluiaraie,  which  probably  has  the  formula, 

OOOC^Hj-  0(CN)Na-  0(OH3)2-  CHg-  COOOgHg, 
is  complete  (see  p.  5^). 

The  crude  product  is  then  directly  treated  with  methylic  iodide, 
when  an  almost  quantitative  yield  of  ethylic  cyanotrimethylglutarate, 
COOO^Hj-  C(CHj)(CN)-  C(CH3)2-  CH^-  OOOOjHg,  is  obtained.  This,  on 
hydrolysis  with  methyl  alcoholic  potash  or  hydrochloric  acid,  yields  the 
beautiful,  crystalline  imide  of  a)3)9-trimethylglutaric  acid, 

which,  when  heated  with  hydrochloric  acid,  at  200°,  is  converted 
quantitatively  into  a/3)9-trimethylglutaric  acid. 

A  direct  comparison  of  the  acid  thus  synthesised  with  that  obtained 
from  camphoric  acid  was  rendered  possible  by  the  kindness  of  Professor 
Balbiano,  who  sent  us  a  sample  of  the  acid  which  he  was  the  first  to 
prepare. 

Both  acids  melted  at  87%  and  on  treatment  with  acetyl  chloride 
yielded  the  same  anhydride  melting  at  82%  and  from  this  by  the 
action  of  aniline  an  anilic  acid  was  prepared  which  in  both  cases 
melted  at  150 — 151%  so  that  there  can  be  no  doubt  as  to  the  identity 
of  the  synthetical  acid  and  Balbiano's  acid. 

In  experimenting  with  a)9)9-trimethylglutaric  anhydride,  it  was 
found  thaty  not  only  does  it  crystallise  from  water  unchanged,  but 
that  it  actually  crystallises  with  water  of  crystallisation,  in  prisms 
melting  at  61%  and  without  being  converted  into  the  acid. 

This  is  certainly  a  very  unusual  property  of  an  anhydridei  and  the 
only  somewhat  similar  case  which  we  have  been  able  to  find  is  that  of 
the  ^lactone  of  dimethylmalic  acid,  (^^^W        QH-OOOH    ^j^.^j^^ 

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64  PERKIN   AND   THORPE:  SYNTHESIS   OF 

as  Baeyer  and  Yilliger  {Ber,,  1897,  30,  1955)  have  shown,  crystallifies 
with  IHgO. 

We  are  at  present  engaged  in  investigating  other  condensations 
between  ansaturated  ethereal  salts  and  a-cyano-ethereal  salts,  and  also 
on  the  action  of  halogen  compounds  on  the  sodium  derivative  of 
ethylic  cjanodimethylglutarate,  and  we  are  especially  interested  in 
the  ethereal  salt  which  this  sodium  derivative  yields  on  treatment 
with  ethylic  bromacetate,  because,  if  Baeyer's  formula  for  isocam- 
phoronic  acid  be  correct,  this  should  lead  to  a  synthesis  of  this  very 
important  acid. 


Ethylic  a-GyanoHi^'Pp'trimeihylgluta/raUy 
COOCgH^-  CH(CN)-C(CH8)2'  CH(CH3)-COOC2H5. 

In  order  to  prepare  this  substance,  ethylic  dimethylacrylate  is 
digested  in  alcoholic  solution  with  the  sodium  derivative  of  ethylic 
cyanacetate,  as  explained  on  page  52,  and  after  heating  for  15  hours 
excess  of  methylic  iodide  is  added  and  the  boiling  continued  until  the 
liquid  has  a  neutral  reaction ;  water  is  then  added,  and  the  oily  product 
extracted  with  ether.  The  ethereal  solution,  after  washing  well  with 
water,  drying  over  calcium  chloride,  and  evaporating,  deposits  a  thick 
oil  which,  after  twice  fractionating,  boils  constantly  at  181°  (25  mm.), 
and  consists  of  pure  ethylic  cyanotrimethylglutarate. 

0*22  gave  11*8  c.c.  nitrogen  at  23°  and  750  mm.     N»5'94. 
CjgHgiNO^  requires  N  =  5'50  per  cent. 

The  yield  of  this  pure  ethereal  salt  obtained  in  this  condensation 
is  about  68  per  cent,  of  the  theoretical,  and  it  is  remarkable  that,  in 
this  case,  only  traces  of  an  acid  ethereal  salt  are  formed,  whereas,  as 
explained  on  p.  52,  if  the  condensation  is  worked  up  before  the  treat- 
ment with  methylic  iodide  the  principal  product  is  the  acid  ethereal 
salt. 

afi^'TrifMthylglutarimide,  C(CH,),<gg|^^«)'gg>NH. 

This  substance  is  formed  when  ethylic  cyanotrimethylglutarate  is 
hydrolysed  either  with  methyl  alcoholic  potash  or  with  concentrated 
hydrochloric  acid  ;  in  the  former  case,  the  product  often  consists  of 
the  acid  amide,  a  white,  deliquescent  solid  which,  however,  can  readily 
be  converted  into  the  imide  by  boiling  for  a  short  time  with  concen-- 
trated  hydrochloric  acid.  a^/3-Trimethylglutarimide  is  sparingly 
soluble  in  cold,  but  readily  in  hot  water,  and  crystallises  in  lon^ 
needles  closely  resembling  )3)3-dimethylglutarimide  (p.  53)  in  appear-- 
ance.     It  melts  at  126°. 


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a/SiS-TRIMBTHYLaLUTAKIC  ACID.  65 

0-1163  gave  9-4  c.c.  nitrogen  at  22°  and  766  mm.     N  =  9-20. 
CgHjjjNOg  requires  N  =3  9-03  per  cent. 

Silver  Malt,  C(CH3)2<25S5o'-^  interesting  salt 

is  obtained  as  a  beautiful,  crystalline  precipitate  when  dilute  ammonia 
is  carefully  added  to  a  warm  solution  of  the  imide  and  silver  nitrate. 

00874  gave  0-0363  Ag.     Ag  =  41  53. 

CgHjgOgNAg  requires  Ag»  41*22  per  cent. 

appTrimethylgluUmc  acid,  COOH-CH(CH3)-0(CH8)2-CH2-COOH. 

This  acid  is  best  prepared  from  the  imide  just  described  by  heating  it 
with  three  times  its  weight  of  concentrated  hydrochloric  acid  in  a  sealed 
tube  for  5  hours  at  200^  The  product  is  evaporated  to  dryness  on 
the  water  bath,  and  the  residue  extracted  with  ether ;  after  drying 
over  calcium  chloride,  the  ethereal  solution  deposits  the  acid  in  an 
almost  pure  condition  on  evaporation.  For  the  analysis,  the  acid  was 
crystallised  from  water,  from  which  it  separates  in  glistening  plates 
melting  at  88°. 

0-1316  gave  0-2675  CO^  and  00960  FgO.     0  =  55-43 ;  H«8-23. 
CgHi^O^  requires  0  =  55-17 ;  H  =  8'05  per  cent. 

aPP-Trtmethylglutaric    Anhydride,    9f^(^58)'C(0H8),-^,  _^j^.g^ 

which  is  the  most  characteristic  derivative  of  aj9)9-trimethylglutaric 
acid,  is  readily  prepared  by  digesting  the  pure  acid  for  a  short  time 
with  excess  of  acetyl  chloride,  and  then  evaporating  to  dryness  on 
the  water  bath.  The  crystalline  residue,  which  consists  of  the  almost 
pure  anhydride,  crystallises  from  a  mixture  of  ethylic  acetate  and  light 
petroleum  in  prisms  which  melt  at  82°. 

0-1446  gave  0-3248  00^  and  0-0991  HA     0  =  61-34;  H  =  7-62. 
OgHigOs  requires  0  =  61-54 ;  H  =  7-67  per  cent. 

This  anhydride  is  quite  insoluble  in  cold  dilute  sodium  carbonate 
solution,  and  is  only  very  slowly  converted  into  the  acid  even  on 
boiling. 

If  this  anhydride  \a  boiled  with  a  large  quantity  of  water,  and  the 
clear  solution,  rapidly  poured  off  from  the  oily  drops,  is  allowed  to 
cool,  a  smaU  quantity  of  the  anhydride  crystallises  out  in  needles  (J) ; 
the  same  substance  is  produced  on  melting  the  anhydride  under  hot 
water  and  stirring  vigorously  until  it  becomes  solid  (II).  The  pro- 
duct in  both  cases  melts  at  61°,  and  consists  of  the  anhydride  with 
half  a  molecule  of  water  of  crystallisation.  The  following  are  the 
results  of  the  analyses  of  specimens  of  I  and  II. 

VOU   MULV.  Digitized  by  QoOgle 


66   DUNSTAN  AND  HENRY:  OCCURRENCE  OF  ORTHOHYDROXY- 

I.  0'2322  gram,  after  drying  on  a  porous  plate  for  3  hours,  lost 

0  0134  gram  at  50°.     HgO  =  5  -8  per  cent. 

II.  0-4712,  heated  at  50°  until  constant,  lost  00242.     H20  =  615. 

CgHjgOg-t-JHgO  requires  H20  =  5'4  per  cent. 

The  water  of  crystallisation  is  given  off  rapidly  on  gently  warming, 
and  slowly  over  sulphuric  acid  in  a  vacuum  desiccator ;  the  residue 
then  melts  at  82°,  the  melting  point  of  the  dry  anhydride. 

afiP-TrimethylglttUbranUie  Add, 

CeHg-NH-  C0-CH(CH8)-  C(CH3)2-  CHj-  C00H(1). 
On  the  addition  of  aniline  to  a  solution  of  the  anhydride  in  benzene, 
this  compound  separates  after  some  time  as  a  white,  crystalline 
precipitate.  After  being  purified  by  recrystallieation  from  dilute 
methylic  alcohol,  from  which  it  separates  in  long  needles,  it  melted 
at  150 — 151°,  and,  on  analysis,  gave  the  following  result. 

0-2515  gave  12*2  c.c.  nitrogen  at  21°  and  752  mm.     N=5'47. 
Ci^HjgNOj  requires  N  =5  5-60  per  cent. 

Our  thanks  are  due  to  Messrs.  F.  Howies  and  F.  H.  Lees,  for  much 
valuable  help  in  connection  with  this  and  the  preceding  research,  and 
we  wish  also  to  state  that  the  very  considerable  expense  which  these 
experiments  have  entailed  has  been  largely  met  by  grants  from  the 
Royal  Society  Research  Fund. 

OwBNs  College, 
Manohbstbr. 


VIII. — Occurrence  of  Orthohydroxyacetophenone  in  the 
Volatile  Oil  of  Chione  glabra. 

By  Wyndham  R.  Dunstan,  F.R.S.,  and  T.  A.  Hbmry,  Salters*  Research 
Fellow  in  the  Laboratories  of  the  Imperial  Institute. 

Some  years  ago,  one  of  us  (Dunstan,  Proc.  Roy,  Soc,  46,  211)  showed 
that  the  strong  foBcal  odour  of  the  wood  of  Celtis  retictUosa  is  due  to 
the  presence  of  skatole,  the  substance  to  which  the  odour  of  human 
excrement  is  due.  Through  the  interest  of  Mr.  Thiselton  Dyer,  the 
Director  of  Kew  Gardens,  other  plants  having  strong  odours  were 
then  examined,  but  no  definite  information  as  to  their  constituents 
could  be  obtained,  owing  to  the  small  quantity  of  material  available 
for  examination.  Amongst  these  plants  was  a  small  specimen  of  the 
wood  of  Chione  glahra,  which  had  been  sent  to  Kew  by  Mr.  J.  H. 
Hart,  F.L.S.,  Superintendent  of  the  Royal  Botanic  Gardens,  Trinidad, 
with  the  suggestion  that  an  examination  of  its  constituents  should  be 

„ .gitized  by  VjOOQ  ,  _ 


ACETOPHENONE  IN  THE  VOLATILE  OIL  OF  CHIONE  GLABRA.      67 

undertaken,  as  the  plant  is  reputed  to  possess  valuable  properties  as  a 
medicine  and,  in  particular,  is  stated  to  be  a  powerful  aphrodisiac.  The 
bark  and  wood  emitted  a  strong,  unpleasant  odour,  chiefly  aromatic, 
but  partly  foecal.  This  was  proved  to  be  due  to  an  oil  which  was  volatile 
with  steam,  and  although  its  chief  physical  and  chemical  properties 
were  ascertained,  the  constitution  of  its  principal  constituent  could 
not  be  determined  owing  to  insufficiency  of  material.  A  further  supply 
of  the  wood  was  afterwards  obtained  from  the  collections  of  the  Imperial 
Institute.  This  was  part  of  a  large  log  which  had  been  sent  previously 
for  exhibition  at  the  World's  Fair  at  Chicago.  Now,  however,  it  has 
completely  lost  its  characteristic  odour,  owing  to  the  escape  of  the 
volatile  oil,  and  it  proved  to  be  quite  useless  for  our  purpose.  Through 
the  kind  offices  of  Mr.  Hart,  the  Trinidad  Government  undertook  the 
collection  of  a  fresh  quantity  of  the  wood,  which  has  made  it  possible 
for  us  to  complete  the  inquiry  by  identifying  the  odorous  constituent 
of  the  tree,  and  in  fact,  proving  its  identity  with  the  substance 
prepared  synthetically  in  the  laboratory. 

The  genus  Chume  of  the  Natural  Order  Ruhtc^cetB  includes  plants 
which  are  confined  almost  exclusively  to  the  West  Indies.  The  species 
Chione  glabra,  which  is  indigenous  to  Grenada,  is  a  large  flowering 
tree,  known  in  the  island  as  *'Yiolette,"  a  name  which  probably 
has  reference  to  the  aromatic  smell  of  the  flower.  Through  the 
kindness  of  Mr.  E.  J.  Millard,  F.C.S.,  we  have  received  from  Grenada 
a  dried  specimen  of  the  stem,  leaves,  and  flowers  of  this  tree.  The 
somewhat  aromatic,  somewhat  foecal,  smell  is  associated  with  the 
bark  and  wood,  especially  with  the  former ;  on  exposure  to  air,  it 
gradually  disappears.  The  results  of  the  chemical  investigation 
described  in  the  subsequent  part  of  this  paper  show  that  the  volatile 
oil,  which  exhibits  in  a  concentrated  form  the  remarkable  odour  of 
the  wood,  is  composed  of  two  substances,  the  one  a  yellow  oil  boiling 
at  160^  under  34  mm.  pressure^  and  solidifying  at  low  temperatures 
to  a  crystalline  mass ;  the  other,  a  colourless^  crystalline  substance 
melting  at  82°.  The  former,  which  is  the  chief  constituent,  we  have 
proved  to '  be  orthohydraxyacetophenone,  OH-C^H^'CO'CHg,  and  is 
identical  with  the  compound  prepared  synthetically.  The  crystalline 
sabetance,  which  is  present  in  very  small  quantity,  has  all  the  proper- 
ties of  analkyl  derivative  of  the  oil ;  the  amount  of  substance  obtained, 
however,  was  insufficient  to  enable  us  to  complete  the  examination. 
The  foecal  odour  of  the  fresh  wood,  which  seems  rather  more  pro- 
nounced than  that  of  the  constituents  we  have  isolated  from  the  oil, 
suggested  the  possibility  that  the  plant  might  also  contain  a  minute 
quantity  of  skatole  or  some  other  derivative  of  indole ;  but  although 
the  volatile  oil  contains  traces  of  somejnitrogenous  substance,  we  have 
not  been  able  to  isolate  any  indole  derivative  from  it.    It  is,  however. 

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68   DUNSTAN  AND  HENRY-:  OCCURRENCE  OF  ORTHOHYDROXY- 

interesting,  and  possibly  significant  from  the  biological  standpoint,  to 
observe  that  derivatives  of  orthohydrozyacetophenone  may,  by 
processes  involving  condensation  and  elimination  of  water,  pass  into 
compounds  belonging  to  the  indole  group  ;  the  production  of  indoxyl 
from  orthacetylamidoacetopbenone  has,  indeed,  been  accomplished  by 
von  Baeyer  and  Bloem  {Ber,^  1884,  17,  963),  and  it  is  not  difficult  to 
conceive  that  the  conversion  may  occur  without  difficulty  and  by 
shorter  steps  in  the  plant.  The  precursors  of  skatole  and  other  indole 
derivatives  in  plants  are  at  present  unknown,  but  the  occurrence  of 
derivatives  of  acetophenone  in  the  vegetable  kingdom  and  particularly 
in  Chione  ghhra^  whose  wood  emits  a  foecal  odour,  indicates  at  least 
one  possible  direction  in  which  search  might  be  mada 

Besides  those  whose  names  we  have  already  mentioned,  we  are 
greatly  indebted  to  Miss  L.  E.  Boole,  F.I.C.,  who  conducted  much  of 
the  preliminary  examination  of  the  constituents  of  this  plant. 

Extraction  qf  the   Volatile  Oil. 

The  volatile  oil  was  separated  from  the  wood  and  bark  by  cutting 
these  into  fine  shavings  and  distilling  with  steam ;  the  distillate 
obtained  was  then  shaken  with  ether,  and  the  ethereal  solution  dried 
over  calcium  chloride  and  distilled.  After  removal  of  the  ether,  there 
remained  a  dark-coloured  oil  which  distilled  with  some  decomposition 
under  the  ordinary  pressure ;  it  was,  therefore,  distilled  under  reduced 
pressure,  when  a  fraction  boiling  from  160°  to  165°,  under  a  pressure  of 
34  mm.,  was  obtained.  With  the  small  quantity  of  material  available, 
it  was  not  possible  to  obtain  a  fraction  of  more  definite  boiling 
point. 

Combustions  of  the  liquid  gave  the  following  results. 

0-0737  gave  01926  OOg  and  00352  HjO.     0  =  71-2;  H  =  5-29. 
00607     „     0-1586  CO2    „    0  0320  H^O.     C  =  71-21 ;  H  =  5-76. 
CgHgOg  requires  C  =  7057  ;  H  =  5*88  per  cent. 

The  relative  density  of  the  oil  is  c^  =  0-850  1574°. 

It  is  slightly  soluble  in  water,  and  has  a  peculiar  and  somewhat 
unpleasant  odour,  chiefly  aromatic,  but  partly  foecal.  An  aqueous  eola- 
tion of  ferric  chloride  produces  a  deep  purple  coloration,  and  bromine 
water  a  faintly  yellow,  crystalline  precipitate.  The  oil  dissolves  in 
alkaline  solutions,  and  such  solutions,  on  evaporation,  leave  a  crystal- 
line salt  or  metallic  derivative ;  the  potassium  and  sodium  salts  crys- 
tallise in  yellow  plates  which  quickly  decompose  on  exposure  to  air  ; 
acids  regenerate  the  oil  from  them. 


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ACETOPHENONE  IN  THE  VOLATILE  OIL  OF  CHIONE  GLABRA.      69 

Action  of  various  Reagents  on  the  Oil. 

Action  of  Acetic  Anhydride.— The  liquid  was  mixed  with  acetic  an- 
hydride and  warmed.  The  viscous  oil  precipitated  on  the  addition  of 
water  to  the  product  was  removed  by  shaking  with  ether,  the 
ethereal  solution  dried,  and  the  ether  removed  by  distillation.  The 
crystalline  residue  of  acetyl  derivative  obtained  on  standing  was  then 
recrystallised  from  methylic  alcohol  until  the  melting  point  was  con- 
stant at  88^.     A  combustion  gave  the  following  result. 

0-1331  gave  03254  COg  and  00776  HgO.     C  =  6666  ;  H  =  64. 
CgHyO-CgHjOa  requires  0  =  67-4  ;  H  =  5-61  per  cent. 

The  substance  is,  therefore,  a  monacetyl  derivative  of  the  original 
liquid,  and  the  existence  of  one  hydroxyl  group  is  thus  proved. 

Action  of  HydroQcylamins  and  Flienyl hydrazine, — When  an  aqueous 
solution  of  hydroxylamine  is  added  to  the  oil  suspended  in  water  and 
the  mixture  gently  warmed,  a  red,  resinous  substance  separates ;  this 
dissolves  in  boiling  water,  and  the  solution  deposits  colourless  needles 
as  it  cools.  These,  after  recrystallisation,  melt  at  112^,  and  have  all 
the  properties  of  an  oxime  of  the  original  substance. 

0-1841  gave  0-4242  COg  and  0-1016  H^O.     0  =  628;  H  =  612. 
OH-CgH^-NOH  requires  C  =  63-4  ;  H  =  5-96  per  cent. 

A  phenylhydrazone  was  also  obtained  by  the  action  of  a  10  per  cent. 
solution  of  phenylhydrazine  on  the  liquid  suspended  in  water ;  after 
24  hours,  this  mixture  deposited  a  greenish-yellow  oil  which  soon 
became  crystalline.    On  recrystallisation,  the  hydrazone  melted  at  108^. 

The  production  of  an  oxime  and  hydrazone  indicate  the  presence  of 
one  ketonic  group  in  the  original  substance. 

Action  qf  Bromine. — When  bromine  water  is  added  to  the  oil 
suspended  in  water,  a  colourless  precipitate  forms  immediately,  and  on 
standing  becomes  crystalline ;  after  recrystallisation  from  hot  alcohol, 
it  melts  somewhat  indefinitely  at  108°,  or,  after  prolonged  heating  at  a 
lower  temperature,  at  95°.  We  are] unable,  at  present,  to  represent 
its  composition  by  any  formula  derivable  from  that  of  the  parent  sub- 
stance. Oombustions  and  two  determinations  of  bromine  by  Oarius' 
method  gave  the  following  results. 

C.  32*6  percent.  H.  2*52  per  cent.         Br.  4564  per  cent. 
32-3       „  2-04       „  46-2 

32-96     „  209       „ 

32-89     „  2-26       „ 

It  will  be  seen  that  these  values  for  carbon,  hydrogen,  and  bromine 
do  not  agree  with  those  required  for  a  mono-  or  dibromo-derivative. 

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70      DUNSTAN   AND  HENRY;  OCCURRENCE  OF  ORTHOHTDROXY- 

CgHyOaBr  requires  0  =  44-6  ;  H  =  3-2  ;  Br  =  37'2. 
CgHgOgBrg      „        C  =  32-6 ;  H  =  204 ;  Br  =  544. 

When  the  bromine  derivative  is  reduced  with  tin  and  hydrochloric 
acid,  it  yields  a  small  quantity  of  a  phenolic  substance  giving  a  bromine 
derivative  melting  at  86^.  It  is  possible  that  the  solid  bromo-deriva- 
tive  is  a  mixture  of  one  or  more  simple  bromine  derivatives,  but 
this  is  not  very  probable,  since  its  composition  seems  to  be  constant 
when  prepared  under  various  conditions,  and  its  melting  point  is  very 
definite. 

Action  of  Fused  Potash. — When  the  oil  is  boiled  for  some  time  (in  a 
vessel  fitted  with  an  upright  condenser)  with  10  per  cent,  potash 
solution,  it  merely  passes  into  a  metallic  derivative,  and  can  be  re- 
covered by  acidifying  the  solution;  and  even  when  heated  with  alkaline 
solutions  in  sealed  tubes  at  125^,  it  is  not  decomposed.  When  fused 
with  excess  of  potash,  the  potassium  salt  of  the  oil  floats  for  a  time  on 
the  excess  of  potash,  but  is  subsequently  completely  decomposed, 
forming  a  dark  brown  mass.  When  this  is  dissolved  in  water, 
acidified,  and  the  mixture  distilled,  a  solution  containing  phenol  is 
obtained  ;  this  was  identified  by  means  of  its  tribromo-derivative. 
When  the  acid  liquid  left  after  distillation  was  extracted  with  ether,  it 
furnished  a  crystalline  substance  which,  after  recrystallisation  from 
hot  water,  melted  at  151°,  and  gave  all  the  reactions  of  salicylic  add 
m.  p.  155°). 

Action  of  Nitric  Add, — ^The  residue  from  the  Carius*  estimations  of 
bromine  in  the  bromo-derivative  was  examined,  and  found  to  contain 
oxalic  acid  and  a  yellow,  crystalline  substance  j  the  quantity  of  the 
latter,  however,  was  too  small  to  admit  of  satisfactory  identification, 
but  since  it  dyed  silk  yellow  and  did  not  dye  cotton,  and  gave  the 
chloropicrin  reaction,  there  can  be  little  doubt  that  it  was  picric  acid. 

These  observations  as  to  the  chemical  behaviour  of  the  volatile 
oil  of  Chione  glabra  prove  that  its  chief  constituent  is  orthohydroxy- 
acetophenone  [OH  :  C0-CH8=  1 :  2]. 

The  facts  may  be  conveniently  summarised  here. 

1.  The  parent  substance  has  a  composition  represented  by  the 
formula  CgHgOg. 

2.  One  of  the  hydrogen  atoms  can  be  replaced  by  the  acetyl 
group,  indicating  the  presence  in  the  parent  substance  of  one  hydrox  jl 
group. 

3.  The  oil  forms  a  monoxime,  having  a  composition  represented  by 
the  formula  OgHgO^N. 

4.  Fusion  of  the  oil  with  potash  furnished  salicylic  acid  and  phenol, 
the  latter  as  the  result  of  secondary  action. 

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ACBTOl»HENONE  IN  THE  VOLATILE  OIL  OF  CfllONE  GLABRA.      71 

The  formation  of  all  these  substances  is  readily  explained  on  the 
assumption  that  the  chief  constituent  of  the  oil  is  orthohydroxy- 
acetophenone,  OH- CgH^-CO'CHg.  This  compound  has  been  described 
by  Tahara  {Ber.,  1892,  25,  1306)  and  by  Eeuerstein  and  Kostanecki 
(Ber.,  1898,  31,  710—719).  The  latter  chemists  described  ortho- 
hydroxyacetophenone  (obtained  by  the  action  of  alcoholic  soda  on 
phenacylidenflavene)  as  a  yellow  oil  of  peculiar  odour,  distilling  at 
218%  giving  a  purple  red  colour  with  ferric  chloride  solution,  and 
forming  a  yellow,  crystalline,  sodium  salt.  Tahara  prepared  the  com- 
pound by  the  decomposition  of  orthomethoxybenzoylacetic  acid.  The 
acetyl  derivative  melted  at  89%  and  the  phenylhydrazone  at  107^. 

We  have  prepared  oxthohydroxyacetophenone  from  nitrocinnamic 
acid,  by  the  following  series  of  reactions.  Orthonitrocinnamic  acid, 
NOj'CgH^'CHICH'COOH,  was  converted  successively  into  dibromonitro- 
phenylpropionic  acid,  NOj-CgH^-CHBr-OHBr-COOH ;  orthonitro- 
propiolic  acid,  NOg'CgH^'CSC'COOH  ;  orthonitrophenylacetylene, 
NOg-CgH^'CiCH;  orthamidophenylacetylene ;  NHg-OgH^-CSCH;  ortho- 
amidoacetophenone,  NHg'C^H^'OO'CHg ;  and,  finally,  by  diazotising 
into  orthohydroxyacetophenone,  OH'CgH^'CO'CHg. 

These  compounds,  with  the  exception  of  the  last,  have  been  prepared 
by  Baeyer  and  Bloem  {Ber.,  1880,  13,  2259),  and  we  have  made  use 
of  the  methods  of  preparation  and  purification  described  by  these 
chemists.  The  orthohydroxyacetophenone  thus  prepared  had  all  the 
characteristics  of  the  oil  distilled  from  Chione  ghhra,  and  furnished 
derivatives  having  the  same  physical  constants;  thus  the  bromine 
derivative  and  the  oxime  melted  at  108°  and  112°  respectively. 

Orthomethox7/<i€etophenone. — ^The  quantity  of  colourless,  crystalline 
substance  left  as  a  residue  in  the  distillation  of  the  crude  chione  oil 
was  too  small  to  admit  of  an  extended  examination,  but  since  it  was 
decomposed  by  boiling  with  hydriodic  acid,  giving  a  volatile  iodide, 
with  the  production  of  an  oil  having  the  properties  of  orthohydroxy- 
acetophenone, it  is  probably  an  ether,  possibly  the  methyl  ether  of 
this  substance.  The  minute  amount  of  this  constituent  present  in  the 
volatile  oil  has  made  it  impossible  for  us  more  certainly  to  identify  it.* 

SciBHTiyic  Depabtmekt, 
Impebial  Institute, 
lokdon,  s.w. 

*  Since  the  work  described  in  the  present  paper  was  completed,  the  following 
account  of  the  Tolatile  oil  of  Chtane  glabra  has  appeared  (Paul  and  Cownley,  Fharm. 
Joum. ,  [i  v],  7»  51).  The  material  examined  was  obtained  from  the  Windward  Islands. 
"From  the  aromatic  odour  of  the  bark,  it  was  conjectured  that  it  might  contain  a 
Tolatile  oil,  and  on  examination  with  that  object  we  succeeded  in  isolating  a  Yolatile 
oQ  amounting  to  about  1  '5  per  cent,  by  weight. 

"  This  yolatile  oil  is  of  a  pale  yellow  colour,  and  has  a  specific  gravity  higher  than 

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72        DUNST*AN  AND  BROWN  :  OCCURHENCE  OF  HYOSCYAMINfi 


IX. — Occurrence  of  Hyoscyamine  in  the  Hyoscyarrvus 
muticus  of  India. 

By  Wyndham  R.  Dunstan,  F.R.S.,  and  Harold  Brown,  Assistant 
Chemist  in  the  Laboratories  of  the  Imperial  Institute. 

Hyo$cyamu8  muticus  is  a  species  of  henbane  which  occurs  in  certain 
districts  of  India,  and  has  long  been  used  in  Indian  medical  practice, 
as  a  particularly  virulent  drug.  The  nature  of  its  alkaloid,  however, 
has  never  been  determined. 

The  following  account  of  the  plant  is  abbreviated  from  that  given 
in  Hooker's  Flora  Indtca. 

ff,  muticus  is  found  in  the  West  Punjab,  in  Scinde,  and  in  Cabul, 
westward  to  Egypt. 

Oauline  leaves,  petioled,  ovate  or  oblong,  entire  or  toothed,  lower 
flowers  pedicelled,  calyx  striate,  pubescent,  teeth  short,  triangular, 
not  acute  in  fruit,  corolla  1  to  1^  inches,  lurid  yellow  or  nearly 
white.  Stem,  1  to  3  feet.  Leaves,  4  to  7  inches,  pubescent,  or  some- 
what woolly,  petiole  ^  to  3  inches.  Lower  pedicles  in  fruit,  j^  to  1  inch. 
Calyx,  §  inch,  in  fruit,  1  by  ^  inch,  funnel-shaped,  ribbed,  somewhat 
reticulate,  villous,  or  ultimately  glabrous  ;  teeth  short,  triangular,  not 
spreading.     Capsule,  ^  inch  in  diameter.     Seed,  ^^  inch  in  diameter. 

The  medicinal  effects  of  this  drug  appear  to  resemble  those  of 
ordinary  henbane ;  when  administered  in  comparatively  large  doses, 
it  acts  as  a  powerful  excitant,  leading  to  what  have  been  described  as 
paroxysms  of  mania,  whence  the  synonym  Hyoacycmvus  insanus.  There 
is  some  reason  to  believe  that  it  has  been  employed  in  the  preparation 
of  certain  extremely  potent  kinds  of  the  Persian  "  Benj  "  and  in  some 
varieties  of  the  Indian  *'  Bhang,"  which,  however,  is  usually  prepared 
from  Indian  hemp.  Since  there  is  at  present  a  considerable  demand  for 
atropaceous  drugs  and  their  alkaloids,  it  seemed  desirable  to  examine 

that  of  water.  It  gave  a  mass  of  acicular  crystals  on  being  cooled  to  about  -  20^. 
The  oil  gave  no  crystalline  compound  with  sodic  bisulphite,  nor  could  evidence  be 
obtained  of  methyl  salicylate.  It  gave  a  semi-solid  mass  on  treatment  with  a  con- 
centrated solution  of  caustic  soda.  It  is  readily  soluble  in  dilute  caustic  soda,  and 
reprecipitated  by  acids  apparently  unaltered.  It  is  slightly  soluble  in  water,  its 
aqueous  solution  gives  a  purple-blue  coloration  with  ferric  chloride.  The  volatile 
oil  is  evidently  a  phenol. 

**  There  are  several  volatile  oils  having  somewhat  similar  properties  to  those  above 
described,  but  the  quantity  of  oil  obtained  was  too  small  to  admit  of  the  further 
examination  which  its  peculiarity  appears  to  deserve." 

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IN   THE  HYOSCYAMUS  MUTlClTS  OF  INDIA.  73 

the  alkaloid  of  this  plant,  which  is  fairly  abundant  in  the  districts  of 
India  in  which  it  is  found,  and  might  possibly  prove  to  be  worth 
exporting. 

Extraction  and  Estimation  of  the  Alkaloid, 

The  sample,  which  weighed  nearly  two  pounds,  was  collected  in 
Scinde,  at  the  instance  of  the  Reporter  on  Economic  Products  to  the 
Government  of  India,  and  consisted  of  both  stems  and  leaves  of  the 
plant ;  these  were  separated  as  far  as  possible,  but  there  remained  a 
mixture  of  fine  stems  and  broken  leaf. 

/  300  grams  leaf. 
Total  weight,  900  grams...  <  310      „      stem. 

(  290      „      mixture  of  ^leaf  and  stem. 

These  three  portions  were  extracted  separately,  in  order  to  deter- 
mine the  proportion  of  alkaloid  in  each. 

The  material  was  air-dried  at  a  low  temperature,  finely  powdered, 
and  then  exhausted  by  percolation  with  cold  alcohol,  the  percolate 
being  evaporated  under  reduced  pressure  until  nearly  the  whole  of  the 
alcohol  had  been  removed.  The  semi-solid  residue  was  then  extracted 
with  dilute  hydrochloric  acid  (0*5  per  cent.),  gently  warmed,  and  well 
shaken;  after  subsidence,  the  acid  liquid  was  poured  o£E  and  the 
treatment  repeated  until  the  alkaloid  was  completely  removed.  The 
acid  solution,  after  filtration,  was  shaken  with  small  quantities  of 
chloroform  in  order  to  remove  the  chlorophyll,  then  made  slightly 
alkaline  by  the  addition  of  dilute  ammonia,  and  the  alkaloid  extracted 
by  successive  shakings  of  the  alkaline  liquid  with  chloroform ;  on  dis- 
tilling off  the  chloroform  under  reduced  pressure,  a  gummy,  alkaloidal 
residue  was  obtained  having  a  slight  odour  recalling  that  of  pyridine. 

A  small  quantity  of  alkaloid  remained  in  the  alkaline  liquid,  and 
could  not  be  removed  by  agitation  with  chloroform  ;  it  was,  however, 
subsequently  isolated  and  examined. 

By  percolation  with  cold  alcohol,  the  following  percentages  of  alkaloid 
were  found. 

In  the  plant  (stem  and  leaf),  680  grams  yielded  0*7  gram  of  alka- 
loid, or  0*1  per  cent  (nearly  pure). 

In  the  stem  only,  310  grams  yielded  0*46  gram  of  alkaloid  (nearly 
pure),  which  is  0*15  per  cent. 

In  the  broken  leaf  and  fine  stems,  250  grams  yielded  0'14  gram  of 
alkaloid  (nearly  pure),  which  equals  0*056  per  cent. 

Examination  of  tlie  Alkaloid, 

In  order  to  identify  the  alkaloid  or  alkaloids  present,  the  impure 
amorphous  residues  were  converted  into  the  aurichloride,  which  was 

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74        DtJNSTAN  AND  BROWN  :  OCCTJRRENCE  OF  HTOSCYAMINE 

examined  by  fractional  crystallisation,  as  described  in  a  previous  paper 
on  the  alkaloids  of  Soopola  Camiolica  (Dunstan  and  Ohaston,  Ph.  /., 
[iii],  20,  461) ;  this  was  obtained  as  a  yellow,  pulverulent  precipitate, 
which  was  recrystallised  from  hot  water  acidified  with  hydrochloric 
acid.  The  alkaloid  from  the  mixed  stem  and  leaf  yielded  two  large 
fractions  of  auric  chloride  melting  at  154 — 156^  and,  after  recrystal- 
lising,  at  167 — 168°,  which  is  very  near  the  melting  point  of  hyos- 
cyamine  aurichloride.  From  the  mother  liquors,  containing  the 
excess  of  auric  chloride,  two  very  small  fractions  of  crystals  were  ob- 
tained melting  at  149 — 160°  and  140 — 146°  respectively  ;  these  were 
too  small  to  be  dealt  with  separately. 

The  alkaloid  from  the  stem  yielded  three  main  fractions  of  auri- 
chloride all  melting  between  164°  and  156°.  On  recrystallising  once, 
three  fractions  melting  at  168°,  167'6°  and  164 — 166°  were  obtained  ; 
by  concentrating  the  mother  liquors  from  these,  two  small  fractions 
melting  at  160 — 165°  and  146 — 160°  were  obtained,  and,  finally,  a  few 
crystals  melting  at  141 — 145°.  The  fractions  of  similar  melting 
points  were  combined  and  recrystallised  from  dilute  acid  until  a  constant 
melting  point  was  attained.  In  the  case  of  the  fractions  of  higher 
melting  point,  two  or  three  recrystallisations  sufficed,  whereas 
the  lower  fractions  required  the  operation  to  be  repeated  at  least 
six  times  before  a  constant  melting  point  was  obtained ;  by  this 
means,  practically  the  whole  of  the  aurichloride  originally  taken 
was  obtained  in  shining  leaflets  melting  at  159*6°.  There  only 
remained  two  small  fractions  melting  at  167 — 158°  and  the  two 
lowest  fractions,  at  140 — 145°,  which  were  too  small  to  be  separately 
dealt  with,  and  were  consequently  retained  and  afterwards  combined 
with  a  fraction  of  similar  melting  point. 

It  is,  therefore,  proved  that  nearly  the  whole  of  the  aurichloride  is 
that  of  hyoscyamine,  which  melts  at  160°  (Ladenburg). 

The  small  quantity  of  alkaloid  which  remained  in  the  alkaline 
liquid  and  was  not  removed  by  agitation  with  chloroform  was  isolated  in 
the  following  manner  (Dunstan  and  Kansom,  Fh.  J.,  [iii],  14, 623).  The 
chloroform  and  alcohol  present  were  removed  by  distillation  under  re- 
duced pressure,  the  liquid  was  acidified,  and  the  whole  of  the  alkaloid 
precipitated  by  adding  a  solution  of  iodine  in  potassium  iodide ;  the 
alkaloids!  periodide  was  collected,  washed,  and  then  decomposed  by  a 
small  quantity  of  a  solution  of  sodium  thiosulphate,  the  liquid 
made  alkaline  with  dilute  ammonia,  and  the  alkaloid  extracted  with 
chloroform.  The  small  quantity  of  alkaloid  thus  obtained  was  con- 
verted into  the  aurichloride,  but  this  could  not  be  recrystallised  and  was 
mixed  with  the  lowest  melting  fractions  (above  referred  to)  for  further 
treatment. 


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IN    THE  HYOSCYAMUS   MUTICU8  OF  INDIA.  75 

Analt/818  qf  the  Aurichloride, 

The  pure  aurichloride  meltiDg  at  159 '5°,  was  analysed,  the  gold, 
chlorine,  and  alkaloid,  being  directly  determined.  A  weighed 
quantity  of  the  salt  was  dissolved  in  water,  the  gold  precipitated  as 
sulphide,  ignited,  and  weighed  as  metal.  After  the  hydrogen  sulphide 
had  been  removed  from  the  filtrate  by  passing  a  current  of  air,  it 
was  exactly  neutralised  with  soda,  and  the  chlorine  determined  by 
titration  with  centinormal  silver  nitrate.  The  filtrate  from  the  silver 
chloride  was  concentrated  in  a  vacuum  over  sulphuric  acid,  then 
made  alkaline  with  dilute  ammonia,  and  the  alkaloid  removed  by 
agitation  with  chloroform,  and  the  residue  obtained  on  distilling  off 
the  chloroform  was  dried  in  a  vacuum  over  sulphuric  acid  until  its 
weight  was  constant. 

I.  0-0636  aurichloride    gave  0*0201  Au,  and  required  422  c.c. 
N/100  AgNOg  (l.cc.  =  0-0003416  CI).     Au  =  31-60  ;  Cl  =  22'66. 

11.  0*0424  aurichloride  gave  0*0134  Au,  and  required  27*8  c.c. 
N/100  AgNOy     Au  =  31*60  ;  CI  =  22*40. 

The  t:wo  solutions  containing  the  alkaloid  from  both  the  above  deter- 
minations were  mixed,  and  the  total  amount  of  alkaloid  estimated. 

0106  aurichloride  gave  0*0491  alkaloid  »  46*32  per  cent. 

Gold.  Chlorine.        Alkaloid. 

Found  31-60,  31-60     2266,22*40     4632 

Calculated  for  CiyHgjNOj^HAuCI^     31*34  2*2-54  45-95 

Another  specimen  of  aurichloride  yielded,  on  ignition,  31*25  per 
cent,  of  gold. 

From  more  of  the  pure  aurichloride,  the  alkaloid  was  regenerated 
by  the  method  above  described,  and  after  recrystallisation  from  a 
mixture  of  dry  chloroform  and  petroleum,  it  was  obtained  in  long, 
silky  needles.  These  were  dissolved  in  absolute  alcohol,  and  the 
specific  rotatory  power  determined.     The  solution  was  Isevorotatory. 

a=:3r.     1=1  dm.     c  =  2-04.     «  =  19°. 

Other  observers  have  recorded  numbers  lying  between  20^  and  21°. 

Hyoscyamus  muticus  as  a  Commercial  Source  of  Pure  Hyoacyamine, 

Having  thus  ascertained  that  the  alkaloid  in  Hyoecyafmis  muticus 
IB  chiefly,  if  not  entirely,  hyoscyamine,  experiments  were  made  to  ex- 
tract the  crystalline  alkaloid  direct  from  the  plant.     For  this  purpose. 

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76  OCCURRENCE  OF  HYOSCYAMINE,  ETC^ 

about  1^  lbs.  of  the  plant,  both  stem  and  leaf,  was  finely  powdered 
and  the  alkaloid  extracted  by  the  method  already  described ;  in  this  way, 
0*7  gram  of  impure  alkaloid  was  obtained  as  a  coloured,  gummy 
residue,  which  could  not  be  crystallised  either  from  ether  or  from 
dilute  alcohol.  By  dissolving  in  dry  chloroform,  however,  and  gradu- 
ally adding  light  petroleum,  the  colouring  matter  was  precipitated, 
together  with  a  little  of  the  alkaloid,  and  a  nearly  colourless  solution 
was  obtained,  from  which,  on  adding  more  petroleum  and  allowing  it 
to  stand,  groups  of  small  needles  were  gradually  deposited. 
Several  fractions  of  the  crystalline  base  were  thus  obtained,  and  were 
recrystallised  in  the  same  manner.  Finally,  pure  hyoscyamine  was 
obtained  in  colourless,  silky  needles  melting  at  105^. 

Absence  qf  other  Mydriatic  Alkaloids. — The  small  quantity  of  alka- 
loid precipitated  along  with  the  colouring  matter  by  the  first  additions 
of  petroleum  to  the  solution  in  chloroform  was  also  examined.  The 
precipitate  was  extracted  with  very  dilute  hydrochloric  acid,  the 
solution  filtered,  and  aurichloride  added,  when  a  yellow  precipitate  was 
produced  which  quickly  aggregated  to  a  resinous  mass  (fraction  A)  ; 
this  was  removed,  and  on  adding  more  of  the  reagent  to  the  filtrate  a 
yellow^  pulverulent  precipitate  was  obtained,  which  did  not  aggregate 
on  standing  (fraction  B).  These  two  fractions  were  recrystallised 
separately  from  dilute  acid ;  from  fraction  A,  two  crops  of  crystals  were 
obtained  melting  at  154 — 155°  and  156 — 158°  respectively;  and  from 
fraction  B,  crystals  were  obtained  melting  at  157 — 158°.  The  mother 
liquors  from  all  these  were  concentrated  in  a  vacuum,  and  thus  a  few 
crystals  melting  at  146 — 149°  were  separated. 

All  fractions  of  aurichloride  insufiicient  for  separate  recrystallisa- 
tion  which  had  been  obtained  in  the  various  experiments  made  were 
finally  combined  into  two  groups  according  to  their  melting  points, 
155 — 158°  and  140 — 145°  respectively.  These  were  recrystallised  as 
before  and  virtually  the  whole  of  the  gold  salt  was  found  to  melt 
constantly  at  169'5°  A  very  small  fraction  melted  at  158 — 159°, 
and  another  from  150—155°,  but  these  were  too  minute  for  further  re- 
crystallisation.  The  following  aro  the  melting  points  of  the  auri- 
chlorides  of  the  chief  mydriatic  alkaloids  :  atropine,  136 — 138°,  hyos- 
cyamine, 159 — 160°;  scopolamine  or  hyoscine,  198 — 199°. 

There  is,  therefore,  no  evidence  of  the  existence  in  this  sample  of 
Hyoscyamus  muticus  of  any  mydriatic  alkaloid  than  hyoscyamine.  We 
believe  that  the  plant  will  prove  to  be  an  important  source  of  this 
alkaloid,  since  it  can  be  isolated  from  it  with  far  less  difiiculty  than 
from  ordinary  henbane  (Hyoscyamus  niger),  which  also  contains  the 
alkaloid  hyoscine,  and  often  atropine  in  addition. 

It  should,  however,  be  remembered  that  the  nature  of  the  alkaloids 
contained  in  atropaceous  plants  appears  to  vary  with  age,  mode  of  culti- 

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PREPARATION  OF  HYPONITRITE,   ETC. 


77 


yation,  and  other  circumstances.  Thns,  in  belladonna,  the  proportion  of 
hyoscyamine  to  atropine  fluctuates  widely  with  the  age  of  the  plant. 
It  is,  therefore,  desirable  that  other  specimens  of  Hyoacyamua  muticua 
should  be  examined,  in  order  to  ascertain  whether  hyoscyamine  is 
invariably  the  only  alkaloidal  constituent. 

It  will  be  convenient  to  summarise  here  our  present  information  as 
to  the  occurrence  of  hyoscyamine  in  various  plants. 

HyoseyamuB  niger  and  cdbua  (hyoscyamine  and  scopolamine). 

Hyoaeyamua  muticua  (hyoscyamine). 

Atropa  heUadonna  (atropine,  hyoscyamine,  and  a  little  scopolamine). 

DiUv^a  sifrcMwnium        „  „  ^ 

DuMsia  myoporoides  (hyoscyamine  and  a  little  scopolamine). 

Scopola  camiolica  (hyoscyamine). 

Scopola  japonica  (atropine,  hyoscyamine,  and  scopolamine). 

Lactuea  aativa  and  viroaa  (hyoscyamine). 

The  following  percentages  of  total  alkaloid  have  been  recorded. 


1 

Hyo9cyamu8  niger. 

Atwpa 

Datura 

Hyoscyamus 

belladonna,  stramonium. 

muticus. 

1 

Biennial. 

Annual. 

BooU. 

0-21-0-41          0-15 

0-155— 0  173 

_ 

LeaTes  0  30-0  90  I^^^^Q.^gj 

ristyr.  0089— 0-069 
\2nd„  0-045—0  068 

andrp.|°-°«*-0-»70 

stem   Xf^.i 
andleafr^ 

Seeds.. 



0  16— 0-37 

0-058— 0-1 



— 

Stem  . 

__ 



■ 

0-46 

Entire 

herb. 

— 

— 

— 

0-03 

— 

We  are  indebted  to  Mr.  E.  A.  Andrews,  Junior  Assistant  in  these 
Laboratories,  for  the  skilful  help  he  has  given  in  the  conduct  of  this 
experimental  work. 

Scientific  Depabtment, 

Impbbial  Institutb,  Londoh. 


X, — Preparation  of  Hyponitrite  from  Nitrite  through 
Hydroxyamidosulphonate. 

By  ErwA&D   Divebs,    M.D.,   D.Sc,    F.R.S.,    and   Tahemasa   Haga, 

D.Sc,  F.C.S. 

SuLPHONATiON,  followed  by  hydrolysis,  readily  converts  an  alkali 
nitrite  into  the  unstable  hydroxyamidosulphonate,  which,  in  a  solution 
saturated  with  potassium  hydroxide,  has  all  its  hydrogen  replaced  by 

„.gitized  by  Google 


78  DIVERS   AND   HAG  A:   PREPARATION   OF   HYPONITRITE 

potassium,  and  is  simultaneously  resolved  into  hyponitrite  and 
sulphite, 

2HO-NH-S08Na  +  4K0H  =  (KON)^  +  2KNaS08  +  iRfi. 

This  remarkable  change  was  made  known  by  us  in  1889  (Trans., 
1889,  55,  760),  along  with  the  fact  that  it  afforded  a  rich  source  of 
hyponitrite,  since  the  quantity  of  the  latter  formed  is  equivalent 
to  at  least  half  the  nitrite  taken.  But  this,  it  was  pointed  out,  de- 
pended on  our  method  of  preparing  hydroximidosulphonate  being 
employed,  and  as  the  description  of  that  method  was  not  published 
until  five  years  later,  the  new  source  of  hyponitrite  could  not  be  used 
advantageously  by  others.  Even  since  then,  the  method  has  escaped  the 
notice  of  seven  separate  workers  on  hyponitrites,  namely,  Thum,  W. 
Wislicenus,  Paal  and  Eietschmer,  Tanatar,  D.  H.  Jackson,  Piloty,  and 
Hantzsch  and  Kaufmann,  to  be  at  last,  however,  taken  up  by 
Kirschner  (Zeit.  anorg,  Chem.,  1898, 16,  424).  Indeed,  it  may  be  said 
to  have  been  rediscovered  by  Piloty,  who  in  a  paper  on  "  an  oxidation 
of  hydroxylamine  by  benzenesulphonic  chloride"  {Ber,,  1896,  29, 
1559),  describes  the  resolution  of  benzenesulphonic  hydroxylamide 
by  potassium  hydroxide  into  hyponitrite  and  benzenesulphinate,  with 
a  yield  also  of  half  the  calculated  quantity  of  the  former  salt. 

As  we  have  each  of  us  very  frequently  employed  the  hydroxyamido- 
sulphonate  method  of  preparing  hyponitrite,  and  the  details  requisite 
in  order  to  get  high  yields  have  not  been  published,  it  seems  it  will  be 
of  service  to  chemists  to  describe  the  method  fully.*  So  far  as  our 
experience  goes,  we  can  be  certain  of  getting  a  yield  of  60  per  cent,  of 
the  theoretical,  and  occasionally  much  more,  although  we  have  not 
succeeded  in  discovering  the  cause  of  this.  In  what  follows,  we  assume 
that  the  convenient  quantity  of  2  decigram-molecules  of  sodium^ 
nitrite  is  taken,  from  which  about  17  grams  of  silver  hyponitrite  may 
be  obtained. 

In  order  to  limit  the  quantity  of  potassium  hydroxide  required, 
which  is  very  large  in  any  case,  no  more  water  than  is  necessary  must  be 
used,  and  except  that  particular  attention  must  be  given  to  this  point, 
the  process  begins  exactly  like  that  of  making  hydroxylamine  sulphate 
from  nitrite  (Trans.,  1896,  69,  1665).  In  a  tared,  wide-mouthed, 
round-bottomed  flask  of  200 — 250  c.c.  capacity,  14'4  grams  of  96  per 
cent,  sodium  nitrite,  f  together  with  sodium  carbonate  containing  10*6 
grams  of  anhydrous  carbonate,  are  dissolved  by  heat  in  enough 
water   to    make    the    total    weigh    83*5    grams.     Some    lead    salt 

*  Eirschner's  method  is  an  excellent  form  of  onr  process,  but  I  prefer  that 
described  in  this  paper. — E.  D. 

t  But  preferably,  18*8  grams  of  pure  sodium  nitrite,  this  being  now  very  easy  to 
prepare  (this  vol.,  p.  86). 

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FBOM   NITRITE  THROUGH  HYDROXYAMIDOSULPHONATE.       79 

in  the  nitrite  is  deposited,  bat  goes  into  solution  when  the  potassium 
hydroxide  is  added  and  gives  no  trouble.  Sodium  carbonate  of  any 
hydration  may  be  used,  but  as,  subsequently,  more  of  this  salt  has  to  be 
added,  and  then  should  be  approximately  the  monhydrate,  it  is  con- 
venient to  use  this  form  throughout.  Such  a  carbonate,  almost  pure, 
is  generally  found  in  the  "  dried "  pure  carbonate  of  commerce. 
Keeping  the  flask  in  active  motion  in  an  ice-and-brine  bath,  sulphur 
dioxide  is  passed  in  until  a  short  time  after  the  temporarily  precipi- 
tated acid  carbonate  has  redissolved,  and  just  when  a  bit  of  lacmoid 
paper  in  the  solution  becomes  fully  red.  About  0*1  c.c.  strong 
sulphuric  acid  is  then  dropped  in.  If  the  temperature  is  kept  below 
0°,  the  conversion  of  the  nitrite  into  hydroximidosulphonate  is  com- 
plete, whereas  if  it  rises  much  above  0^  some  nitrilosulphonate  would 
form,  and  interfere  with  the  result.  If  higher  temperatures  have 
been  avoided,  the  nitrite  and  carbonate  taken  in  molecular  propor- 
tions, and  the  sulphur  dioxide  not  used  in  excess,  the  solution  is  ready 
to  be  hydrolysed  ;  but  as  the  salts  may  not  have  been  in  exact  propor- 
tion, and  sulphur  dioxide  may  also  be  present,  it  is  best  to  blow  a 
strong  current  of  air  through  the  solution  at  0^,  so  as  to  expel  any 
sulphur  dioxide  or  nitric  oxide  that  may  be  present. 

After  this  treatment,  the  solution  is  brought  to  about  30°,  in  order 
to  start  hydrolysis,  and  set  aside  for  a  day  in  a  warm  place  with  the 
flask  corked.  Complete  hydrolysis  to  hydroxyamidosulphonate  with- 
out further  hydrolysis  to  hydroxylamine  is  thus  secured,*  and,  conse- 
quently, just  the  calculated  quantity  of  sodium  carbonate  (10'8  grams 
anhydrous)  is  found  to  be  required,  including  that  for  the  three  or 
four  drops  of  sulphuric  acid  added.  The  approximately  monhydrated 
carbonate,  added  in  fine  powder,  is  briskly  shaken  with  the  solution, 
so  as  to  hinder  its  caking,  the  last  portions  being  dissolved  by 
warming  the  flask.  The  solution  of  hydroxyamidosulphonate  and 
sulphate,  thus  prepared,  contains  almost  exactly  half  its  weight  of 
water,  is  therefore  supersaturated,  and  is  the  strongest  solution 
practically  obtainable;  it  will  be  found  to  approach  closely  113  grams 
in  weight,  so  smoothly  do  the  reactions  proceed.     The  solution  may 

*  That  the  production  of  hydroxylamine  is  avoided  if  this  detail  is  attended  to, 
has  been  proved  by  shaking  the  solution,  after  it  has  been  made  alkaline,  with 
sodium  amalgam,  which  readily  converts  hydroxylamine  into  ammonia,  but  does  not 
act  on  the  hydroxyamidosulphonate.  On  testing  in  this  way,  no  odour  of  ammonia 
can  be  renognised,  and  moist  red  litmus  paper  held  in  the  bottle  is  barely  affected. 
Eirschuer,  using  potassium  hydroximidosulphonate,  had  to  heat  to  boiling  to  effect 
hydrolysis,  which  is  difficult  then  to  complete  without  some  of  the  hydroxyamido- 
sulphonate passing  on  into  hydroxylamine.  When  the  hydrolysis  is  incomplete, 
nitrite  will  be  regenerated  later  on  by  the  alkali ;  and  when  it  is  earned  too  far, 
nitrite  will  also  be  formed  during  the  oxidation  of  the  hydroxylamine  by  the  silver 
(or  mercury)  oxide.- 


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80  DIVEBS  AND  HAOA :  PREPARATION  OF  HTPONITRITE 

be  made  weaker,  and  then  concentrated,  but  the  adjustment  is 
troublesome,  and  the  formation  of  hard  cakes  of  sodium  sulphate, 
which  interferes  with  the  proper  working  at  the  next  stage  of  the 
operation,  is  difficult  to  avoid. 

The  contents  of  the  flask  are  now  well  drained  into  a  basin,  prefer- 
ably a  hemispherical  nickel  basin,  or,  lacking  that,  a  stout  porcelain 
one,  capable  of  holding   about  500  c.c.    Potassium  hydroxide,  free  from 
chloride,  assayed  for  real  alkali  and  for  water,  and  having   not   less 
than  two-thirds  and  not  more  than  1  mol  of  water  to  1  of  the  hydroxide, 
is  required,  for  if  it  were  anhydrous  it  would  cause  much  heating  and 
consequent   decomposition   of   the   salts;    generally,    the  potassium 
hydroxide  purified  by  alcohol  and  the  more  translucent  varieties  of 
stick   potash   contain  about   the   right   proportion    of    water,    and 
dissolve  in  water  without  much  rise  of  temperature.     From  130  to  165 
grams    of    it,  according  to    its  degree  of  hydration,  are  quickly 
crushed  in  a  warm  mortar,  thrown  into  the  solution  in  the  basin, 
and   incorporated  with  it  by  means  of  a  pestle.     There  is  marked 
heating  only  just  at  first,  which  is  better  met  by  keeping  the  basin  in 
water  or  resting  it  on  snow  or  pounded  ice  for  a  very  short  time.     On 
stirring  in  the  potassium  hydroxide,  the  solution  sets  to  a  stiff  paste, 
if  kept  cold,  quickly  becoming  thin  again  on  further  stirring,  but  full 
of  an  opaque,  white   precipitate  of  sulphate.     If  the  basin  has  been 
cooled,  hardly  any  gas  escapes  at  first,  but  gentle  effervescence  and 
much  frothing  occur  before  long  in  any  case.     When  the  potassium 
hydroxide  has  been  all  ground  up  and  dissolved,  the  basin  is  placed 
under  close  cover  from  atmospheric  moisture  and  carbonic  acid,  and 
left  in  a  warm  place  for  30  hours ;  if  kept  for  more  than  50  hours,  the 
quantity  of  hyponitrite  sensibly,  but  slowly,  diminishes.     As  much 
even  as  one-fourth  of  the  hydroxyamidosulphonate  may  sometimes,  in 
cold  weather,  still  be  present,  and  can  be  partly  destroyed  by  keeping 
the  basin  at  55 — 60°  for  half  an  hour,  although  not  with  noticeable 
increase  of  the  quantity  of  hyponitrite,  but  this  heating,  with   the 
attendant  risk    of   over-heating,  is    better   omitted,  on  the  whole. 
Besides  undecomposed  hydroxyamidosulphonate,  the  contents  of  the 
basin  now  consist  of  precipitated  sulphate  and  sulphite,  and  solution 
of  potassium  hydroxide  in  slightly  less  than    its  weight  of  water 
(almost  exactly  KOH :  3H2O),   together  with  the   potassium   hypo- 
nitrite.    It  is,  apparently,  only  to  secure  this  concentration  of  the 
potassium  hydroxide,  a  practically  saturated  solution,  that  hardly  less 
than  10  mols.  of  it  to  1  of  hydroxyamidosulphonate  have  to  be  used. 
More  of  it  may  be  added  without  effect,  good  or  bad,  unless  the  solu- 
tion of  the  salts  is  weaker  than  is  here  recommended,  for  in  that  case 
additional  potassium  hydroxide  must  be  used  to  bring  the  concentra^ 
tiontothe  right  point. 

Digitized  by  VjOOQIC 


FROM  NITRITE  THKOUaH   HYDROXYAMIDOSULPHONATE.       81 

Treatment  with  a  silver  salt  is  the  only  way  of  separating  the 
hyponitrite  from  the  other  salts,  and  for  this  purpose  the  presence  of 
the  alkali  is  essential,  together  with  large  dilution  when  precipitating. 
The  best  way  is  to  use  the  silver  solution  exceedingly  dilute,  because 
this  checks  the  precipitation  of  silver  oxide  and  sulphite  until  some 
time  after  all  the  hyponitrite  has  separated.  Now  the  necessity 
for  large  dilution,  and  the  advantage  of  still  larger  dilution,  remove 
the  only  objection  that  can  be  raised  to  the  use  of  silver  sulphate 
instead  of  ^ver  nitrate,  and  since  it  is  generally  important  to  feel 
assured  that  no  trace  of  nitrate  or  nitrite  can  have  been  carried  down 
with  the  hyponitrite,  the  sulphate  should  have  the  preference,  although 
the  nitrate  can  almost  certainly  be  used  with  as  good  results.  A  cold 
saturated  solution  contains  only  5  or  6  grams  of  the  sulphate  to  the 
litre,  and  is  most  easily  prepared  by  boiling  excess  of  the  salt  with 
water  and  pouring  the  solution  into  an  equal  volume  of  cold  water. 

Whichever  salt  is  used,  the  contents  of  the  basin  are  first  washed 
into  a  very  capacious  precipitating  vessel,  and  the  highly  dilute  silver 
solation  is  poured  in  until  it  ceases  to  produce  any  more  black 
precipitate.  When  this  is  at  all  abundant,  as  it  sometimes  is  in 
cold  weather,  an  hour's  interval  is  given  for  subsidence  of  most  of 
it,  the  still  dark  solution  is  decanted,  and  the  precipitate  washed  by 
decantation  before  rejecting  it.  With  or  without  this  interruption, 
the  addition  of  the  silver  solution  is  continued  until  the  bright  yellow 
hyponitrite  suddenly  appears,  and  so  long  after  as  the  joint  precipita- 
tion of  brown  oxide  can  be  easily  checked  by  stirring.  When  the 
point  IB  reached  where  the  oxide  only  redissolves  slowly  and  no  longer 
gives  place  to  a  yellow  one  of  hyponitrite,  no  more  silver  solution 
should  be  added.  If  much  more  were  added,  there  would  be  permanent 
precipitation  of  silver  oxide,  which  is  apt  to  be  accompanied  by 
silver  sulphite.  The  quantity  of  silver  sulphate  required  may  be 
as  much  us  40  grams,  which  means  7  or  8  litres  of  solution ; 
if  silver  nitrate  be  used,  about  44  grams  will  be  wanted,  dissolved  in 
4  litres,  or  more,  of  water. 

Half-an-hour  after  precipitation,  the  solution  is  to  be  poured  off, 
even  though  still  a  little  turbid,  and  the  precipitate  washed  by 
decantation,  for  there  is  a  very  slow  deposition  of  a  mirror  of 
metallic  silver  from  the  sulphite  solution,  which  goes  on  for  days.  In 
order  to  separate  the  hyponitrite  from  the  metallic  silver  and  its 
oxide,  and  perhaps  chloride,  it  has  to  be  dissolved  in  dilute  acid  and 
reprecipitated.  If  every  trace  of  nitrite  is  to  be  kept  out  of  the 
hyponitrite,  nitric  acid  can  hardly  be  used,  because  I  find  that  it 
always  contains  some  nitrous  acid,  and.  it  is,  therefore,  necessary  to 
use  sulphuric  acid.  Since  the  hyponitrite  must  be  kept  in  solution  as 
short  a  time  as  possible,  it  is  advisable  to  have  the  acid  not  very 

VOU    LXXV.  Digitized  by  Gdbgle 


82  ABSORPTION  OP  NITRIC  OXIDE  IN  GAS  ANALYSIS. 

dilute,  in  order  to  reduce  the  volume  of  liquid  to  be  filtered.  But 
high  dilution  is  better,  because  the  stability  of  hjponitrite  falls 
off  rapidly  with  increasing  concentration;  moreover,  if  the  sul- 
phuric acid  is  not  dilute  enough,  silver  sulphate  will  separate; 
a  1  per  cent,  solution  of  the  acid,  well  cooled  in  ice,  is  suitable, 
some  5  litres  of  it  being  required.  The  precipitate  should  be  treated 
with  the  acid  in  portions  at  a  time,  not  all  together;  and,  as  far  as 
possible,  the  undissolved  precipitate  should  be  kept  off  the  filter  until 
the  last.  For  so  long  a  filtration  a  Lunge  filter-tube-extension  of  the 
funnel  is  more  suitable  than  the  filter  pump,  the  filtrate  being  allowed 
to  fall  directly  into  excess  of  sodium  carbonate  solution.  Working 
with  these  precautions,  the  silver  hyponitrite  can  be  dissolved  and 
reprecipitated,  even  in  hot  weather,  with  hardly  any  appreciable  loss. 

Having  replaced  the  alkaline  mother  liquor  by  water,  dilute  sul- 
phuric acid  is  cautiously  added,  until,  after  stirring  up  the  precipitate 
well,  the  solution  is  no  longer  alkaline,  and  some  of  it,  when  filtered, 
is  found  to  contain  a  trace  of  the  silver  hyponitrite ;  this  is  best  ascer- 
tained by  adding  one  or  two  drops  of  sodium  carbonate  solution  to 
about  100  C.C.  of  it,  which  should  cause  a  permanent,  yellow,  very 
slight,  opalescence. 

The  precipitate,  thoroughly  washed  by  decantation  and  dried  on  a 
filter  at  the  ordinary  temperature  in  a  desiccator,  in  the  dark,  and 
then  at  100°,  will  give  78  per  cent,  silver  (calc.  78-26).  But  in  order 
to  preserve  the  bright  colour  of  the  salt  and  its  entire  freedom  from 
nitrite,  all  work  on  it  should  be  done  with  very  little  exposure  to 
bright  daylight.  The  weight  of  silver  hyponitrite  obtained  from  the 
quantity  of  sodium  nitrite  employed  should  be  not  less  than 
17  grams. 

Imperial  Tokyo  Univeesity,  Japan. 


XI. — Absorption  of  Nitiic  Oxide  in  Gas  Analysis. 

By  Edward  Divers. 

It  is  well  known  that  the  vapour  tension  of  nitric  oxide,  dissolved  in 
the  solution  of  a  ferrous  salt,  interferes  with  the  use  of  this  reagent 
to  remove  nitric  oxide  from  other  gases.  There  is,  however,  another 
absorbent  for  nitric  oxide  which  leaves  nothing  to  be  desired,  whose 
use  and  value  have  remained  unknown.  This  is  a  strong  solution  of 
either  sodium  or  potassium  sulphite  to  which  a  little  alkali  hydroxide 
has  been  added.  It  quickly  absorbs  every  trace  of  nitric  oxide,  which 
it  fixes  in  the  form  of  hyponitrososulphate,  NajN^OjSO^.      I  have 

_. ,  ^oogle 


IMTEBAGTION   OF  NITBIC  OXIDE  WiTH  SILVER   NITRATE.      83 

already  made  satisfactory  use  o^  it  to  analyse  the  mixture  of  nitric 
oxide  and  nitrogen  which  is  left  on  heating  silver  hyponitrite  and 
allowing  the  solid  and  gaseous  products  to  cool  in  contact  with  each 
other.  The  sulphite  need  not  be  very  pure,  the  presence  of  sulphate 
or  carbonate  being  of  no  importance.  If  carbon  dioxide  or  other  acid 
gas  is  present  along  with  the  nitric  oxide,  it  is  removed  by  alkali 
before  using  the  sulphite  mixture. 


XII. — Interaction  of  Nitric  Oxide  with  Silver  Nitrate. 

By  Edward  Divers. 

Having  reason  to  think  that  silver  nitrate  might  interact  with  nitric 
oxide  if  heated  in  it,  and  there  being  no  information  obtainable  on 
this  point,  I  have  made  some  experiments  on  the  action  of  nitric  oxide 
on  silver  nitrate,  as  well  as  on  other  nitrates. 

In  the  first  place,  something  had  to  be  ascertained  as  to  the  be- 
haviour of  silver  nitrate  when  heated  alone.  Heated  for  15  minutes 
in  dry  air  or  carbon  dioxide,  it  suffers  no  chemical  change  until  the 
temperature  is  close  to  the  melting  point  of  sulphur  (444^),  and  the 
slight  decomposition  which  occurs  at  that  temperature,  being  accom- 
panied by  an  action  on  the  glass,  may  be  due  to  that  action.  A 
minute  quantity  of  oxygen  seems  to  be  liberated,  and  there  is  a  very 
alight  greying  of  the  faintly  yellow  liquid  ;  on  cooling  and  dissolving, 
there  is  slight  turbidity  from  the  presence  of  silver,  and  a  trace  of 
nitrite  can  be  detected.  Only  at  a  much  higher  temperature  does  the 
Bait  decompose  with  free  effervescence,  and  then  nitric  peroxide 
accompanies  the  oxygen,  and  silver  is  deposited  ;  even  then,  nitrite 
is  present  in  the  mass  only  in  very  small  quantity  at  any  time,  there 
never  being  enough  to  remain  undissolved  when  the  nitrate  is  treated 
with  a  little  water.  This  is  sufficient,  however,  to  show  that  the  pri- 
mary decomposition  of  silver  nitrate  by  heat  alone  is  into  silver  nitrite 
and  oxygen,  the  instability  of  silver  nitrite  at  much  lower  tempera- 
tures, although  diminished  by  the  presence  of  nitrate  (Trans.,  1871, 
24,  85),  accounting  fully  for  its  being  found  in  such  small  quantity 
when  the  temperature  is  high,  and  for  the  production  of  nitric  peroxide 
and  silver  instead.  As  determined  by  Carnelley,  the  melting  point  of 
silver  nitrate  is  217''. 

The  nitric  oxide  used  for  the  experiments  was  prepared  by  the 
ferrous  sulphate  method,  stored  for  2  days  in  a  glass  gas-holder,  and 
dried  in  its  passage  to  the  silver  nitrate  by  a  sulphuric  acid  column.  At 
starting,  the  air  in  the  drying  apparatus  and  in  the  tube  containing 

_. pJoogle 


84      INTERACTION  OF  NITRIC  OXIDE   WITH  SILVER   NITRATE. 

the  silver  nitrate  was  expelled  by  carbon  dioxide,  the  silver  nitrate 
being  heated  in  the  gas,  in  order  to  dry  it.  Interaction  between  the 
silver  nitrate  and  the  nitric  oxide  was  recognised  by  the  reddening  of 
,  the  gas,  and  at  the  end  of  an  experiment  the  gases  were  expelled  by 
carbon  dioxide  before  opening  the  tube. 

Silver  nitrate,  when  heated  in  nitric  oxide,  is  strongly  affected  by 
it,  being  freely  decomposed  at  a  much  lower  temperature  than  that 
at  which  it  decomposes  when  heated  alone,  the  nitric  oxide  becoming 
oxidised.  The  action  commences,  perhaps,  at  150^  but  this  is  doubtful ; 
at  the  melting  point  of  the  salt,  it  becomes  marked,  and  at  the  boiling 
point  of  mercury  considerable,  but  even  at  this  temperature  it  is  a 
long  time  before  the  decomposition  is  complete,  the  progress  of  the 
change  gradually  becoming  slower.  For  some  time,  the  products  are 
silver  nitrite  and  nitric  peroxide,  AgNOg  +  NO  =  AgNOg  +  NOj,  but 
very  little  silver  is  liberated,  the  nitrite  being  almost  wholly  pre- 
served for  a  long  time,  through  combination  with  the  undecomposed 
nitrate.  But  when,  as  the  nitrate  becomes  decomposed,  the  nitrite 
is  no  longer  unprotected,  it  suffers  decomposition,  as  usual,  into 
silver  and  nitric  peroxide  ;  finally,  nothing  but  silver  remains. 

Theoretically,  it  is  quite  probable  that  nitric  oxide  does  not,  after 
all,  act  directly  on  silver  nitrate.  For,  making  the  allowable  suppo- 
sition that,  to  a  minute  extent,  silver  nitrate  decomposes  into  silver 
nitrite  and  oxygen,  at  temperatures  much  below  that  at  which  it  does 
so  sensibly,  the  nitric  oxide  ma^  be  regarded  as  being  active  by  com- 
bining with  this  oxygen,  and  thus,  by  removing  it,  greatly  hastening 
the  spontaneous  decomposition  of  the  nitrate.  This  decomposition, 
thus  assisted,  and  occurring  at  temperatures  at  which  silver  nitrite  is 
comparatively  stable  in  presence  of  nitrate,  the  nitrite  remains,  although 
at  higher  temperatures  it  decomposes  almost  as  fast  as  it  is  formed 
from  the  nitrate.  According  to  this  theory,  silver  nitrate  is  not 
actually  decomposed  by  nitric  oxide,  but  only  decomposes  much  more 
rapidly  in  its  presence,  in  consequence  of  its  interaction  with  one  of 
the  products  of  decomposition.  For  practical  purposes,  silver  nitrate 
and  nitric  oxide  may,  however,  be  treated  as  acting  on  each  other 
when  heated  together. 

Nitric  oxide  has  no  action  on  sodium  potassium  or  barium  nitrate, 
even  at  the  temperature  of  boiling  sulphur. 

Lead  nitrate  soon  begins  to  decompose  by  heat  alone,  and  nitric 
oxide  seems  to  be  without  effect  on  its  decomposition.  According  to 
Stas,  lead  nitrate  begins  to  decompose  somewhere  above  200° ;  I  find 
that,  for  its  fairly  free  decomposition,  a  temperature  not  much  below 
400°  is  required.  At  the  boiling  point  of  sulphur  even,  the  decompo- 
sition proceeds  at  such  a  moderate  rate  that  only  after  10  minutes 
heating  does  the  salt  show  distinct  signs  of  fusing.     No  nitrite  is  pro- 

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DIVERS  :  PKEPARATION  OF  PURE  ALKALI  NITRITES.  85 

duoed,  bat  a  very  little  peroxide  of  lead  is  formed.  By  washing  the 
mass  with  cold  water,  and  then  boiling  it  out  with  water,  the  beauti- 
ful, crystalline,  white  salt,  Fb(0H)N03,  can  be  obtained  in  abundance. 


XIII. — Preparation  of  Pure  Alkali  Nitrites. 
By  Edward  Divers. 

When  pure  sodium  or  potassium  nitrite  is  wanted,  it  is  customary  to 
prepare  silver  nitrite  from  crude  alkali  nitrite,  and  convert  this  again 
into  alkali  nitrite  by  means  of  sodium  or  potassium  chloride.  The 
crude  nitrite  must  be  nearly  free  from  sulphate,  and  either  before  or 
after  adding  the  silver  nitrate  to  it,  nitric  acid  must  be  added  until  all 
the  hydroxide  and  carbonate  are  neutralised.  The  silver  nitrite  is  got 
in  the  most  convenient  form  for  washing  by  precipitating  it  from  con- 
centrated solutions.  Silver  chloride  is  very  sensibly  soluble  in  a 
concentrated  solution  of  alkali  nitrite,  and  when  the  solution  is  no 
longer  clouded  by  the  addition  of  more  alkali  chloride,  it  already 
contains  this  salt  in  excess.  Therefore,  somewhat  large  dilution  is 
necessary,  and  this  entails,  of  course,  much  evaporation  afterwards. 

The  silver  nitrite  process  is  evidently  not  a  very  satisfactory  one, 
and  when  sodium  nitrite  is  wanted  pure,  it  is  better  to  recrystallise, 
three  times  over,  the  commercial  96  per  cent,  sodium  nitrite,  well 
draining  each  time  on  the  suction  funnel.  A  concentrated  solution 
of  the  crude  salt  should  be  left  to  clear  from  lead  turbidity  for  two 
days,  or  be  filtered  cold  through  a  fine  filter ;  the  lead  carbonate  is 
more  soluble  in  the  hot  nitrite  solution  than  in  the  cold.  After 
separating  the  lead,  the  solution  should  be  fully  neutralised  with 
nitric  acid  before  evaporation  for  crystallising.  Potassium  nitrite  is 
too  soluble  and  deliquescent  to  be  conveniently  purified  in  a  similar  way. 

A  most  satisfactory  and  simple  process  for  preparing  either  sodium 
or  potassium  nitrite,  when  the  pure  hydroxide  or  carbonate  is  at 
command,  is  to  saturate  this  with  red  nitrous  fumes  under  appropriate 
conditions.  That  nitrites  can  be  thus  obtained  is  known  to  every 
chemist,  was  known  to  Ckky-Lussac  in  1816,  and  was  described  by 
Fritzsche  in  1840,  but  it  has  hitherto  been  stated  and  believed  that 
much  nitrate  is  then  unavoidably  formed  along  with  the  nitrite. 
That  is  a  mistake,  and  therefore  this  note  is  published.  If  obvious 
precautions  of  the  simplest  kind  are  taken,  so  little  nitrate,  if  any,  is 
formed  as  to  be  hardly  detectable  with  certainty  in  presence  of  so 
much  nitrite.  Consequently,  if  the  quantity  of  pure  alkali  taken  is 
known,  a  solution  of  given  strength  in  nitrite  is  perhaps  better 
prepared  in  this  way  than  in  any  other. 

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86  DIVERS  :   PREPARATION   OF  PURE  ALKALI  NITRITES. 

Avoiding,  so  far  as  practicable,  the  use  of  cork  and  caoutchouc, 
nitrous   gases,  from   nitric   acid   and  starch  or  arsenious  oxide,  are 
passed  into  the  concentrated  solution  of  the  hydroxide  or  carbonate 
until  the   alkali   is   quite  neutralised.      Sodium  carbonate  alone  is 
somewhat  inconvenient,  because  of  its  sparing  solubility,  but  this  may  be 
circumvented  by  adding  it,  finely  divided  and  in  sufficient  quantity,  to 
its  own  saturated  solution,  just  before  passing  the  gases  and  by  often 
shaking  the  vessel  during  their  absorption.     To  prevent  free  access  of 
air,  the  nitrite  is  prepared  in  a  flask  with   its   mouth  kept  loosely 
closed  while  the  gases  are  passing;  it  is  not  necessary  to  cool  the 
flask.     The  strength  of  the  nitric  acid  and  the  temperature  of  the 
generator  of  the  nitrous  gases  must  be  so  regulated  that  just  a  little 
nitric  oxide  is  in  excess  of  the  nitric  peroxide,  and  therefore  is  passing 
unabsorbed,  as  a  guarantee  that  the  latter  does  not  act  on  the  solution 
in  absence  of  its  equivalent  of  the  former  and  thus  produce  some 
nitrate.     To  free  the  gases  from  volatilised  nitric  acid,  they  may  be 
passed  through  a  bottle  or  tube,  either  empty  or  packed  loosely  with 
cotton.     The  finished  solution  must  be  almost  neutral,  and  if  acid 
must  be  boiled  until  neutral,  before  exposing  it  to  the  air.     A  concen- 
trated solution  of  alkali  nitrite  dissolves  a  little  nitrous  acid  without 
decomposing  it,  as  water  alone  would.     To  get  the  salt  in  the  solid 
state  or  to  crystallise  out  the  sodium  nitrite  where  it  is  necessary  to 
be  sure  of  absence  of  all  nitrate  in  it,  the  solution  may  be  freely 
evaporated,  even  at  a  boiling  heat,  without  decomposing  or  oxidising  it. 
The  alkali  nitrites  have  been  very  imperfectly  described,  and  need 
examination.      In  the  meantime,  some  points  in  their  description  are 
here   given.     Sodium   nitrite   and   potassium  nitrites  are  distinctly 
though  faintly  yellow,  and  give  markedly  yellow  solutions  in  a  little 
water.     They  are  very  slightly  alkaline  to  litmus.     At  15°,  6  parts  of 
sodium  nitrite  requires  6  parts  of  water  to  dissolve  it;    potassium 
nitrite  is  soluble  in  about  one-third  of  its  weight  of  water.     Sodium 
nitrite  melts  at  271°  (mercury-thread  immersed).     Sodium  nitrite  is 
moderately  deliquescent,  remaining  dry  in  winter-cold  air ;  potassium 
nitrite  is  exceedingly  deliquescent,  and  is   obtained  in   very   small, 
thick,  prismatic  crystals,  whilst  sodium  nitrite  crystallises  in  very 
thin,   flattened   prisms,   often   very   large.     Sodium   nitrite    is  well 
known  to  be  anhydrous ;  not  so  potassium  nitrite,  crystals  of  which 
are  reputed  to  contain  ^H^O.     I  have,  however,  examined  small,  but 
distinct  and   separate,  crystals   taken  from  the  upper  part  of  some 
kilos,  of  the  commercial  salt,  which  had  become  well  drained  by  long 
standing.     They  were  removed  in  very  dry  weather  and  weighed,  and 
then  found  to  lose  hardly  1    per  cent,   on  fusion.     The  anhydrous 
character  of  the  potassium  salt  was  further  ascertained  by  testing  a 
cake  of  minute  crystals,  prepared  by  myself,  which  had  been  pressed, 

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REDUCTION  OF  AN  ALKALI  NITRITE  BY  AN  ALKALI  METAL.      87 

under  cover,  between  porous  tiles,  in  cold,  dry  air ;  the  loss  of  weight 
on  heating,  much  above  100%  was  a  little  over  1  per  cent.,  and  the 
percentage  of  potassium  was  45*30,  instead  of  45*88,  required  for  the 
anhydrous  salt. 

Somewhat  remarkably,  the  point  as  to  hydration  of  potassium 
nitrite  was  examined  independently  in  the  same  year,  1863,  by  Lang 
and  by  Hampe,  with  identical  results,  indicating  the  composition 
expressed  by  2KNO2  +  H2O,  but  both  these  chemists  made  the 
determination  on  a  magma  of  indistinct  crystals,  which  had  been 
di'ied  in  a  vacuum  desiccator. 


XIV. — Reduction  of  an  Alkali  Nitrite  by  an  Alkali  Metal. 

By  Edward  Divers,  M.D.,  D.Sc.,  F.R.S. 

It  is  already  known  what  are  the  products  which  may  result  from  the 
action  of  sodium  amalgam  on  a  solution  of  sodium  nitrate  or  nitrite. 
Schonbein  (1861)  first  observed  the  formation  of  nitrite  by  the  action 
of  metallic  sodium  on  a  solution  of  a  nitrate;  and  de  Wilde  (1863) 
that  nitrous  oxide,  nitrogen,  and  ammonia  are  the  products  of  the 
action  of  sodium  amalgam  on  a  solution  of  potassium,  sodium,  or  am- 
monium nitrate,  or  on  potassium  nitrite ;  he  found  that,  except  alkali 
hydroxide,  nothing  else  is  produced,  and,  in  particular,  no  hydrogen. 
Some  years  later  (1870),  however,  it  was  recognised  by  Fremy, 
aided  by  a  suggestion  of  Maumen^'s,  that  hydroxylamine,  or  what 
appeared  to  be  hydroxylamine,  was  a  product  of  the  reduction.  Then 
came  (1871)  my  own  discovery  of  the  hyponitrites,  together  with  the 
observation  that  alkali  nitrates  in  solution  are  largely  convertible  into 
nitrites  by  sodium  amalgam,  an  extension  of  Schonbein's  experience. 
Lastly,  Haga  and  I  (1896)  proved  that  the  actively  reducing  sub- 
stance observed  by  Fremy  is  actually  hydroxylamine,  as  it  had  been 
taken  to  be  by  Maumen6  and  by  him,  and  not  hydrazine,  as  it  might 
have  been.  By  a  mistake,  already  pointed  out  and  corrected  by  me 
{Annalen^  1897,  295,  366),  the  discovery  of  the  hyponitrites  has  been 
in  recent  years  attributed  to  Maumen^.  It  will  suffice  here  to  say 
that  this  veteran  French  chemist  has,  it  so  happens,  published,  in 
another  connection,  that  he  had  not  experimentally  investigated  the 
redaction  of  nitrites  in  solution,  and  that^  far  from  laying  claim  to  the 
discovery  of  hyponitrites,  he  at  first  denied  its  truth  on  theoretical 
gronnds  (Trans.,  1872,  25,  772 ;  Chem.  News,  25,  153  and  285). 

Nitrons  oxide,  nitrogen,  hydroxylamine,  ammonia,   sodium  hypo- 
nitrite,  and  sodium  hydroxide  (from  the  nitrite  as  well  as  from  the 

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88  divers:  reduction  of  an 

metal),  are,  according  to  my  experience,  always  produced  in  the  re- 
duction of  sodium  nitrite  or  nitrate  by  sodium  amalgam,  but  in  pro- 
portions which  vary  greatly  within  well-marked  limits.  Nearly 
one-sixth  of  the  nitrogen  can  be  obtained  as  sodium  hyponitrite  in 
one  way  of  working,  or  scarcely  any  at  all  in  another.  So,  too,  the 
range  of  production  of  hydroxylamine  is  from  nearly  9  per  cent,  of  the 
nitrogen  of  the  nitrite  down  to  one-third  per  cent.  The  presence  of 
ammonia  may  be  very  strongly  manifest,  or  be  hardly  perceptible  and 
escape  notice.  The  two  gases,  nitrous  oxide  and  nitrogen,  together 
represent  at  least  80  per  cent,  of  the  total  nitrogen,  and  may  vary  in 
relative  proportion  to  the  extent  of  either  of  them  being  nearly 
absent.  Necessarily,  all  the  sodium  of  the  nitrate  or  nitrite,  not  left 
as  hyponitrite,  appears  as  hydroxide,  along  with  that  derived  from 
the  metallic  sodium  used  as  the  reducing  agent.  So  long  as  any 
nitrite  remains,  hydrogen  does  not  occur  among  the  products,  unless 
a  very  large  quantity  of  water  is  present,  whilst,  if  there  is  very 
little  water,  hydrogen  is  not  evolved  even  after  all  the  nitrite  is 
gone. 

Within  the  limits  indicated,  the  proportioning  of  the  products  of 
the  reduction  is  well  under  control.  The  conoentration  of  the  solu- 
tion of  nitrite,  or,  to  put  it  better,  the  relative  quantity  of  water 
present,  exercises  most  influence,  the  only  other  circumstance  affect- 
ing the  course  of  the  reduction  being  the  temperature.  The  concen- 
tration of  the  sodium  in  the  amalgam  and  the  proportions  of  the 
sodium  and  the  nitrite  have  no  direct  effect  on  the  reduction.  Work- 
ing with  a  sufficiently  concentrated  solution  of  nitrite,  the  proportions 
of  the  products  remain  constant  throughout  the  reduction  of  the 
nitrite.  Probably  this  is  the  case  also  when  an  exceedingly  dilute 
solution  is  used ;  but  with  a  somewhat  dilute  solution,  say  1  in  30, 
there  is  some  difference,  due  to  the  fact  that  the  presence  or  absence 
of  much  sodium  hydroxide  modifies  the  proportions  of  the  products, 
and  that  this  substance  is  generated  so  largely.  A  dilute  solution  of 
sodium  nitrite  may  be  made  to  behave  as  a  concentrated  solution  in 
the  mode  of  its  reduction  by  nearly  saturating  it  with  sodium 
hydroxide  before  bringing  it  in  contact  with  the  sodium  ama^;am ;  but 
the  addition  of  sodium  hydroxide  to  a  concentrated  solution  of  nitrite 
before  reducing  it  by  the  amalgam  has  no  sensible  effect,  for  the 
reason,  no  doubt,  that,  in  the  reduction  of  the  nitrite  as  it  actually 
occurs,  about  3^  mols.  of  sodium  hydroxide  are  produced  for  1  mol.  of 
nitrite  reduced,  quite  enough,  therefore,  of  itself  to  make  the  water  of 
a  concentrated  solution  almost  proof  against  the  action  of  sodium. 
With  a  large  quantity  of  water  present,  the  sodium  hydroxide  formed 
is  not  enough  to  render  the  water  inactive,  and  in  this  is  to  be  found 
the  explanation  of  the  great  difference  observed  in  the  proportions  of 

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ALKALI  NITRITE  BT  AN   ALKALI  METAL.  89 

the  products,  according  as  the  nitrite  is  dissolved  in  much  or  little 
water. 

In  order  to  produce  as  much  kyponitrite  as  possible,  little  more  is 
necessary  than  to  work  with  a  concentrated  solution  of  the  nitrite 
(1  of  sodium  nitrite  to  3  or  3^  water),  to  add  the  amalgam  in  some 
excess,  and  not  to  allow  the  temperature  to  rise  above  100^.  To 
get  as  much  kydroxylamine  as  possible,  the  solution  of  nitrite  must 
be  dilute  (say  1  in  60),  and  be  kept  cold  during  the  addition  of  the 
amalgam.  To  preserve  the  hydroxy lamine  from  reduction  to  ammonia, 
the  solution  must  be  kept  well  agitated  over  the  amalgam,  and  be 
poured  off  from  it  as  soon  as  nearly  all  the  nitrite  has  been  reduced. 
Much  more  time  is  needed  to  reduce  a  dilute  solution  than  a  concen- 
trated one.  The  best  conditions  for  producing  much  hydroxylamine 
do  not  allow  of  much  more  than  half  the  maximum  yield  of  hypo- 
nitrite  being  obtained  at  the  same  time. 

To  get  much  nitrous  oxidej  the  temperature  of  the  solution  must  be 
kept  as  low  as  possible,  whilst  to  get  much  nUrogenf  the  temperature 
must  be  kept  high,  the  strength  of  the  solution  of  nitrite  being 
without  effect.  The  reduction  of  a  very  dilute  solution  of  sodium 
nitijte  kept  very  cold  is  attended  with  very  little  effervescence, 
because  the  quantity  of  nitrogen  produced  is  very  small  and  the  nitrous 
oxide  remains  dissolved,  although  it  is  readily  evolved  on  warming. 
De  Wilde  has  determined  the  proportions  of  the  gases  to  each  other, 
but  only  when  the  nitrite  (or  nitrate)  was  in  excess  of  the  sodium  ;  that 
however,  is  sufficient,  since  qualitative  examination  of  the  gases  has 
shown  me  that  variations  in  the  proportions  of  salt  and  metal  are 
without  sensible  influence  on  the  composition  of  the  gases,  and  also 
that  this  remains  apparently  unchanged  during  the  progress  of  the 
reduction  if  the  temperature  is  kept  tolerably  uniform.  De  Wilde 
found  that  dilute  solutions  of  nitrite  or  nitrate  of  sodium  or  potassium 
gave  larger  quantities  of  nitrous  oxide  in  proportion  to  nitrogen  when 
the  solutions  were  dilute  than  when  they  were  concentrated,  from 
which  it  might  seem  that  the  strength  of  the  solution  does  affect  the 
proportions  of  the  gases  to  each  other;  but  in  the  experiments 
conducted  by  de  Wilde,  the  much  greater  rise  of  temperature  when 
concentrated  solutions  are  acted  on  fully  accounts  for  the  results  he 
obtained. 

Ammonia  can  always  be  detected  from  the  beginning  of  the  reduc- 
tion (Thum  thought  not),  but  its  amount  may  be  minute  throughout. 
It  can  be  got  in  considerable  quantity  by  using  a  cold  dilute  solution, 
as  for  producing  hydroxylamine,  and,  after  the  main  action  is  over, 
shaking  it  with  amalgam  in  a  stoppered  bottle  until  all  the  hydroxyl* 
amine  has  disappeared.  It  can  also  be  got  somewhat  concentrated 
for  a  short  time  by  dropping  the  concentrated  solution  of  the  nitrite  on 

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90  DIVERS!   KEDUCTION   OF  AN 

to  much  solid  sodium  amalgam,  as  was  first  observed  by  de  Wilde 
but  even  then  much  hyponitrite  is  produced.  Very  hot  and  dilute 
solutions  of  nitrite  treated  with  sodium  amalgam  give  little  else  than 
ammonia  and  nitrogen. 

The  reduction  of  potassium  nitrite  by  potassium  amalgam  closely 
resembles  that  of  the  sodium  salt  by  sodium  amalgam,  in  every  respect, 
both  quantitative  and  qualitative. 

If,  for  the  moment,  nitrogen  and  hydrozylamine  be  disregarded,  as 
they  well  may  be,  since  their  proportions  become  very  small  under 
suitable  circumstances,  the  nitrite  may  then  be  said  to  be  reduced 
simply  to  hyponitrite  and  much  of  this  hydrolysed  into  nitrous 
oxide  and  sodium  hydroxide.  This,  at  one  time,  I,  as  well  as  other 
chemists,  supposed  to  be  the  case.  But,  for  a  long  time  now,  I  have 
felt  that  most  of  the  nitrous  oxide  and  sodium  hydroxide  must  have 
another  origin.  Thum  has  expressed  himself  in  the  same  sense, 
basing  his  opinion  upon  the  comparative  stability  of  sodium  hyponitrite 
in  strongly  alkaline  solution,  for  it  is  only  gradually  decomposed  even 
when  boiled  with  it.  This  fact  by  itself,  however,  is  not  inconsistent 
with  the  assumption  that  the  nitrous  oxide  and  sodium  hydroxide 
represent  decomposed  hyponitrite.  But  it  does  not  stand  alone ;  for 
(a)  Hot  concentrated  solutions  of  nitrite  yield  quite  as  much 
hyponitrite  as  cold  ones,  unless  the  temperature  is  well  above  100°, 
and  even  then  the  yield  does  not  fall  off  much.  (6)  In  all  cases,  the 
effervescence  accompanying  the  formation  of  hyponitrite  goes  on 
exclusively  at  the  surface  of  contact  with  the  amalgam,  (c)  Low 
production  of  hyponitrite  is  not  attended  with  higher  production  of 
nitrous  oxide.  All  these  facts  are  opposed  to  the  view  that  the  nitrite 
is  all  reduced  to  hyponitrite  in  the  first  place  ;  so,  too,  is  what  follows. 
Although  the  proportions  of  the  products  of  the  reduction  of  the 
nitrite  vary  greatly  with  the  circumstances,  it  is  only  within  well- 
marked  limits  J  thus,  of  the  nitrite  reduced  there  is  from  a  sixth , 
under  one  set  of  conditions,  to  almost  a  fifth,  under  other  conditions, 
which  becomes  partly  hyponitrite  and  partly  hydroxylamine  (and 
ammonia),  whilst  the  rest  becomes  nitrogen  and  nitrous  oxide,  one  or 
the  other  predominating,  according  to  circumstances.  So,  too,  in  one 
extreme  case,  nearly  all  of  the  one-sixth  of  the  nitrite  will  change 
into  hyponitrite,  very  little  becoming  hydroxylamine ;  or,  on  the 
other  hand,  of  nearly  one-fifth  of  the  nitrite  more  than  half  may  be 
converted  into  hydroxylamine,  only  the  rest  of  the  fifth  becoming 
hyponitrite.  It  may,  therefore,  safely  be  assumed  that  about  one- 
fifth  of  the  nitrite  tends  to,  or  is  able  to,  become  hyponitrite, 
although  barely  one-sixth  of  the  nitrate  can  yet  be  secured  as  this 
salt,  because  either  some  of  this  fifth  becomes  hydroxylamine,  or 
else  a  little  of  the  hyponitrite  is  hydrolysed  at  once  or  during  the 

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ALKALI  NITRITE  BT   kN  ALKALI  METAL.  91 

process  of  isolating  it.  With  that  assumption  to  give  more  precision 
to  the  statement,  it  may  be  affirmed  that  many  experiments  under 
varied  ^conditions  have  shown  that  about  a  fifth  of  the  nitrite  is 
decomposed  by  sodium  amalgam  in  one  way,  and  four-fifths  in 
another  way ;  in  the  one,  hyponitrite,  hydroxy lamine,  and  alkali 
(with  a  very  little  ammonia  and  nitrous  oxide  as  secondary 
products)  are  formed,  and  in  the  other,  nitrogen,  nitrous  oxide,  and 
alkali;  so  that  when  much  hydroxylamine  is  formed  it  is  at  the 
expense  of  hyponitrite  only,  and  when  much  nitrogen  is  produced  it 
is  at  the  expense  of  the  nitrous  oxide  only. 

But  although  this  is  the  case,  the  hydroxylamine  does  not  seem  to 
be  derived  from  the  hyponitrite,  or  the  nitrogen  from  the  nitrous 
oxide,  but,  rather,  the  one  pair  of  substances  is  derived'  from  one 
transition  product,  and  the  other  pair  from  another  transition 
product.  It  was  pointed  out  in  my  first  paper  that  sodium  amalgam 
does  not  act  on  hyponitrite,  and  this  has  since  been  more  fully 
established  by  Dunstan  and  Dymond,  and  again  by  Thum ;  according 
to  the  last-named  chemist,  hyponitrous  acid  is  not  reduced  even  by  zinc 
and  boiling  dilute  sulphuric  acid.  In  confirmation  of  my  earlier  state- 
ment^  I  can  now  assert  that  sodium  amalgam  has  no  action  whatever 
on  a  solution  of  sodium  hyponitrite  saturated  with  sodium  hydroxide, 
even  at  80°  (and,  no  doubt,  at  higher  temperatures),  and  when  in  con- 
tact with  it  for  days  together ;  no  hydroxylamine,  ammonia,  nitrogen^ 
or  hydrogen  is  produced.  In  weaker  alkaline  solutions,  hydrogen  is  very 
slowly  evolved,  but  still  without  the  hyponitrite  being  affected.  Weak 
alkaline  solutions  of  sodium  hyponitrite,  however,  slowly  decompose 
of  themselves,  and  then  some  of  the  nitrous  oxide  may  possibly  get 
reduced  by  the  sodium  amalgam. 

As  for  the  nitrogen,  it  is  evident  that  only  while  nitrous  oxide 
remains  in  solution  and  comes  in  contact  with  the  amalgam  can  it  be 
reduced,  even  if  it  is  then  (see  p.  95).  Yet,  in  order  to  get  much 
nitrogen  in  place  of  nitrous  oxide,  it  is  necessary  to  work  with  hot 
solutions,  when  the  solubility  of  nitrous  oxide  is  at  its  lowest.  It  is 
not  essential  that  the  quantity  of  nitrite  should  be  small  in  propor- 
tion to  the  sodium,  temperature  alone  appears  to  be  the  condition 
determining  the  formation  of  nitrogen  in  place  of  nitrous  oxide.  In 
other  words,  weak  solutions  of  nitrite  and  excess  of  amalgam  in  no 
degree  favour  the  production  of  nitrogen  rather  than  of  nitrous 
oxide,  and  the  proportion  of  nitrogen  is  not  greater  in  the  gases 
escaping  towards  the  end  of  a  reduction  than  at  the  beginning. 

YeTy  different  is  it  with  ammonia,  which  is  truly  a  product  of  the 
reduction  of  hydroxylamine  (in  non-acid  solution),  and  the  formation 
of  which  takes  place  principally  during  the  final  action  of  the 
amalgam.     Against  the  notion,  highly  improbable  as  it  is,  that  the 

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92  DIVERS:   REDUPTION  OF  AN 

nitrogen  may  come  from  yet  undecomposed  nitrite  and  already  formed 
ammonia,  which  would  also  account  for  the  comparative  absence  of 
ammonia  in  the  earlier  part  of  the  reduction,  there  may  be  adduced 
de  Wilde's  observation,  that  ammonium  nitrate,  when  reduced  by 
sodium  amalgam,  gives  much  more  nitrous  oxide  in  proportion  to 
nitrogen  than  potassium  or  sodium  nitrate  does,  no  doubt  because 
there  is  less  rise  in  temperature. 

Without  speculating  on  the  constitution  of  a  nitrite,  we  are  able  to 
see  from  the  interactions  between  ethylic  iodide  and  silver  nitrite 
that  a  nitrite  may  react  both  as  an  oxylic  salt,  NaONO,  and  as  a 
halide,  NaNOj.  From  the  reduction  by  sodium  there  will  then  first 
result  the  radicles  NaON=  and  NaNO ;  from  the  former,  or  sodox- 
imido-radicle,  may  well  come  the  hyponitrite  and  hydroxylamine,  and 
from  the  other,  or  sodium  nitroside  radicle,  the  nitrous  oxide  and 
nitrogen.  In  accordance  with  the  facts  observed,  the  sodoximide,  in 
concentrated  alkaline  solution,  will  condense  to  sodium  hyponitrite, 
stable  against  reduction,  or,  in  very  dilute  alkaline  solution,  will,  by 
hydrolysis  and  reduction,  become  alkali  and  hydroxylamine.  The 
hypothetical  nitroside  will  also  condense  and  simply  hydrolyse  into 
nitrous  oxide  and  alkali,  mainly  at  low  temperatures,  or  will  become 
reduced  and  hydrolysed  into  nitrogen  and  alkali,  principally  at  higher 
temperatures. 

To  establish  the  points  in  the  reduction  of  the  two  nitrites  by  their 
respective  metals,  here  described,  I  have  made  very  many  experiments, 
usually  working  on  quarter-gram  molecules  of  nitrite.  The  hypo- 
nitrite obtained  was  weighed  as  silver  salt.  The  hydroxylamine  was 
estimated  by  the  quantity  of  metallic  silver  it  yielded,  and  in  this 
way :  the  black  precipitate  it  causes  in  silver  nitrate  solution,  in 
presence  of  alkali,  being  largely  suboxide,  was  washed  with  cold 
dilute  nitric  acid  and  ammonia  alternately,  and  the  residual  brownish 
metallic  silver  weighed  and  calculated  into  hydroxylamine  by  the 
ratio  2Ag:Nn30,  experiments  (described  in  the  next  paragraph) 
with  solution  of  hydroxylamine  sulphate  of  similar  dilution  and 
alkalinity  having  shown  that  this  could  be  done  accurately  enough. 

The  important  observation,  made  by  Thum,  that  hydroxylamine, 
when  oxidised  by  suitably  alkalised  mercuric  oxide,  silT^r  oxide,  or 
cupric  hydroxide,  will  yield  a  little  hyponitrite  and  nitrite,  induced  me 
to  ascertain  whether,  in  my  experiments,  the  destruction  of  hydroxyl- 
amine in  this  way,  sometimes  in  considerable  quantity,  might  not 
account  for  some  of  the  hyponitrite  afterwards  found  to  be  present. 
To  ascertain  whether  this  took  place,  I  made  a  blank  experiment  very 
similar  to  those  made  in  studying  the  reduction  of  sodium  nitrite^ 
except  that  sodium  hyponitrite  itself  was  absent.     Thus,  hydroxyl- 

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ALKALI  NItBITE  BY   AN  ALKALI  MBTAL.  93 

Amine  sulphate,  1*5  grams  (^0*6  gram  hydrozylamine)  was  dissolyed 
along  with  32  grams  of  sodium  hydroxide  in  nearly  2  litres  of  water,  and 
then  a  sedation  was  ran  in,  with  stirring,  of  7*6  grams  of  silyer  nitrate, 
which  was  a  considerable  excess,  sach  as  was  ased  in  the  other  experi- 
ments. The  abandant,  black  precipitate  was  washed,  exhaosted  with 
ice  cold,  dilate  nitric  acid,  and  the  eolation,  neatralised  as  asaal  in  my 
other  experiments,  gave  no  silver  reaction  for  sUver  hyponitrite,  and 
nothing  more  than  a  slow  and  yery  slight  action  on  permanganic  acid, 
which  might  be  dae  to  a  trace  of  either  nitrons  or  hyponitroas  acid. 
It  was  easily  seen  that  some  nitrons  acid  was  formed,  by  applying  the 
iodide  and  starch  test.  Under  the  circamstances  of  my  experiments, 
therefore,  even  when  7  per  cent,  of  the  nitrite  had  been  reduced  to 
hydroi^lamine,  there  coald  have  been  no  perceptible  prodaction  of 
hyponitrite  daring  the  after  oxidation  of  the  hydroxylamine.  The 
metallic  silver,  washed  out  with  dilate  nitric  acid  *  and  ammonia, 
weighed  3*8  grams,  the  calculated  quantity  being  3*95  grams.  The 
nitrite  detected  in  the  mother  liquor  of  the  black  precipitate  had 
been  formed  in  too  small  a  quantity  to  materially  affect  the  weight  of 
the  metallic  silver. 

Generally,  sodium  hydroxide  was  approximately  estimated,  after  all 
the  hyponitrite  had  been  precipitated,  by  titration  Of  the  mother  liquor 
with  nitric  acid,  and  of  the  silver  oxide  that  had  been  precipitated  along 
with  the  silver  hyponitrite  and  the  metallic  silver.  The  amalgam  used 
was  of  approximately  known  strength,  ascertained,  not  by  sampling, 
which  is  impracticable,  but  by  uniformly  preparing  successive  quanti- 
ties, and  sacrificing  one  to  assay  by  dilute  sulphuric  acid  and  weighing 
the  sodium  as  sulphate ;  after  use  in  reducing  nitrite,  the  sodium  re- 
maining in  the  mercury  was  sometimes  determined  in  the  same  way. 
Nitrous  oxide  and  nitrogen  were  not  measured ;  their  total  nitrogen 
was  foand  by  difference,  and  their  proportions  had  been  sufficiently 
ascertained  by  de  WUde,  as  I  have  already  said ;  but  their  relative 
abundance  was  estimated  by  a  burning  splint  of  wood,  the  reduction 
of  the  nitrite  being  always  conducted  in  a  loosely  closed  flask.  The 
range  of  this  reaction  was  from  that  of  a  gas  utterly  extinguishing 
eombostion  to  that  of  one  which  supported  it  most  vividly ;  in  any 
miifonnly  conducted  experiment,  the  gases  evolved  towards  the  end 
behaved  like  those  given  off  at  first. 
To  ascertain  the  effect  on  its  reduction  by  sodium  of  adding  sodium 

*  It  WM  proyed  many  yean  ago  that  silver  is  inaolable  in  dilate  nitric  acid,  the 
pfeienoe  of  nitrons  acid  being  necessary  to  make  it  dissolye.  Bat  the  contrary  has 
been  since  asserted  to  be  trae  where  the  silyer  is  finely  divided,  as  when  precipi- 
tated. This  error,  as  1  most  regard  it,  is  due  to  precipitated  silver  when  black  or 
M^>vf^i>  containing  snboxide,  which  gives  it  its  colour :  this  b  resolved  by  acids 
into  oride  of  nlver,  which  dissolves,  and  metallic  silver,  which  is  left. 

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94     BEDUGTION  OF  AN  ALKALI  KITRITK  BT  AN  ALKALI  METAL. 

hydroxide  to  a  concentrated  solution  of  sodium  nitrite  (negative  as 
this  proved  to  be),  two  methods  were  adopted.  In  one,  the  amalgam 
was  covered  with  a  cold  saturated  solution  of  sodium  hydroxide) 
which  has  no  action  on  it,  and  then  the  concentrated  solution  of  nitrite 
was  slowly  added ;  at  first,  the  alkali  greatly  impedes  the  action  of 
the  amalgam  on  the  nitrite,  but  when  more  of  the  solution  of  the 
latter  is  added,  the  action  goes  on  faster  and  to  the  end,  and  gives  the 
usual  large  proportion  of  hyponitrite  with  very  little  hydroxylamine. 
In  the  other,  a  concentrated  solution  of  sodium  nitrite  and  sodium 
hydroxide  was  treated  with  some  of  the  amalgam ;  then  more  sodium 
nitrite  was  added,  and  then  more  amalgam.  The  result  was  the  same 
as  before.  The  object  of  working  in  this  way  was  to  obtain  the 
effect,  if  any,  of  the  most  concentrated  alkali  from  the  firsts  without 
having  to  deal  afterwards  with  a  very  large  excess  of  alkali  when  the 
analysis  had  to  be  made. 

I  have  also  tried  to  ascertain  the  effect  of  diminishing  the  amount 
of  alkali  present.  In  acid  reducing  mixtures,  nitrous  acid  becomes 
largely  converted  into  hydroxylamine  without  production  of  hypo* 
nitrous  acid,  so  that  it  seems  probable  that,  could  the  alkali  formed  in 
the  reduction  of  the  nitrite  by  sodium  be  neutralised  nearly  as  fast  as 
it  is  produced,  much  hydroxylamine  would  be  obtained  and  very  little 
hyponitrite.  The  use  of  the  ordinary  acids  for  the  purpose  in  such  a 
way  as  to  give  conclusive  evidence  on  the  point  does  not  seem  to  be 
practicable,  whilst  «the  great  rapidity  of  the  process  of  reduction 
makes  the  use  of  carbon  dioxide  (Aschan,  ^ar.,  1891,  24^  1865)  very 
unpromising.  I  have,  therefore,  tried  the  effect  of  adding  ammonium 
acid  carbonate  along  with  the  sodium  nitrite,  expecting  the  ammonia 
to  be  inactive.  In  one  case,  where  I  used  the  amalgam  in  large 
excess,  much  ammonium  amalgam  was  formed,  and,  what  was  quite 
unexpected,  neither  hyponitrite  nor  hydroxylamine.  In  another 
experiment,  in  which  the  nitrite  was  kept  in  excess  of  the  amalgam, 
the  previous  addition  of  the  ammonium  carbonate  in  excess  was 
without  any  effect ;  the  nitrite  solution  had  to  be  used  slightly  dilute 
because  of  the  carbonate,  and  gave,  therefore,  a  little  less  hyponitrite 
(about  12*7  per  cent,  of  the  nitrite  consumed)  and  a  little  more 
hydroxylamine  (about  3  per  cent.)  than  in  the  best  way  of  working  for 
hyponitrite.  The  presence  of  the  ammonium  carbonate  was,  therefore, 
without  effect,  the  reaction  between  the  nitrite  and  the  sodium  being 
already  complete  when  the  sodium  oxide  comes  in  contact  with  the 
water  and  ammonium  carbonate. 

I  satisfied  myself  that  a  fairly  concentrated  solution  of  nitrite  is 
uniformly  reduced  from  the  commencement  to  the  end  of  the  reaction 
if  the  temperature  is  kept  tolerably  constant,  the  method  employed 
being  to  examine  the  gases  in  the  way  described,  and  the  hyponitrite 


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BIVER8 :  HTPOKITBITES  ;  THEIB  PBOPERTIfiS,  ETC.  95 

Udd  bydrozylamiiKe  as  follows.  To  a  solution  of  nitrite,  one-half  only 
of  the  quantity  of  sodium  amalgam  required  to  reduce  it  was  added, 
and  it  was  then  found  to  contain  hyponitrite  and  hydrozylamine  in 
the  same  relative  proportion  as  if  the  nitrite  had  been  f uUy  reduced 
(with  cooling),  and  in  apfHrozimately  half  the  quantities  the  nitrite 
would  have  yielded  if  the  f  uU  amount  of  sodium  amalgam  had  been 
added. 

Sodium  amalgam  was  proved  to  have  little  or  no  action  on  nitrous 
oxide  by  exposing  the  gas  for  a  long  time  to  its  action.  The  amalgam 
was  liquid,  and,  when  shaken  up  with  the  moist  nitrous  oxide  in  a 
stoppered  bottle,  coated  the  sides  of  the  bottle.  With  occasional 
vigorous  shaking,  the  bottle  was  kept  closed  four  days ;  when  opened, 
it  was  found  to  contain  the  nitrous  oxide  little,  if  at  all,  deteriorated 
as  a  supporter  of  combustion.  In  another  similar  experiment,  a 
saturated  solution  of  sodium  hydroxide  was  poured  over  the  amalgam  ; 
in  this  case,  the  amalgam  did  not  coat  the  sides  of  the  bottle,  but  the 
solution  served  to  keep  the  dissolved  nitrous  oxide  in  contact  with  the 
amalgam.  The  bottle  was  often  vigorously  shaken,  and  was  not 
opened  until  after  four  days.  The  nitrous  oxide  was  almost  or  quite 
unchanged.  Holt  and  Sims  have  studied  the  oxidation  of  soditmi  and 
potassium  by  nitrous  oxide,  but  only  at  much  highcor  temperatures 
than  those  in  these  experiments,  which  were  at  26 — 30^. 

Imfbrial  Tokyo  Uhiyebsitt,  Japak. 


XV. — Hyponitrites ;  their    Properties^  and  their   Pre- 
paration  by   Sodium  or  Potassium. 

By  Edward  Diybbs,  M.D.,  D.Sc.,  F.R.8. 

Thb  hyponitrites  have  received  the  attention  of  many  chemists 
besides  myself  since  their  discovery  in  1871,  and  even  this  year  new 
ways  of  forming  them  and  the  new  working  of  an  old  method  have 
been  published.  Yet  much  has  been  left  to  be  put  on  record  before  a 
fairly  correct  and  full  history  of  these  salts  can  be  said  to  have  been 
given,  and  the  present  paper  is  meant  to  be  the  necessary  supplement 
to  what  has  already  been  published. 

Ways  qf  forming  Hyp<mi4TiU8, 

Ko  writer  on  hyponitrites  in  recent  years  has  shown  himself 
acquainted  with  all  the  known  ways  of  getting  these  salts,  <x  even 
with  the  most  productive.    The  following  complete  list  is  valuable, 

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96     OITERS:  HTPONITRITES  ;  TH|SIR  PR0PEBTIE8,   AND  TflEIB 

therefore^  and  is  of  special  interest  as  bringing  together  the  various 
modes  o?  formation  of  these  salts: 

1.  Reduction  of  an  alkali  nitrite  by  the  amalgam  of  its  metal 
(Divers,  1871). 

2.  Beduction  of  an  alkali  nitrite  by  ferrous  hydroxide  (Zom,  1882 ; 
Dunstan  and  Dymond). 

3.  Reduction  of  (hypo)nitrososalphates  by  sodium  amalgam  (Divers 
and  Haga,  1886). 

4.  Reduction  of  nitric  oxide  by  alkali  stannite  (Divers  and  Haga, 
1885). 

5.  Reduction  of  nitric  oxide  by  ferrous  hydroxide  (Dunstan  and 
Dymond,  1887). 

6.  Decomposition  of  a  hydroxyamidosulphonate  by  alkali  (Divers 
and  Haga,  1889). 

7.  Oxidation  of  hydroxylamine  by  sodium  hypobromite  (Kolotow, 
1890). 

8.  Oxidation  of  hydroxylamine  by  mercuric  oxide,  silver  oxide,  or 
cupric  hydroxide  (Thum,  1893). 

9.  Interaction  of  hydroxylamine  and  nitrous  add  (Thum,  H.  Wis- 
lioenus,  Paal  and  Elretschmer,  Tanatar,  1893). 

10.  Oxidation  of  hydroxylamine  by  bensenesulphonic  chloride  and 
alkali  (Piloty,  1896). 

11.  Interaction^  in  methylic  alcohol,  of  hydroxylamine  with  nitrous 
gases  (Ejiufmann,  1898,  Annalen,  200,  98). 

12.  Interaction,  in  methylic  alcohol,  of  hydroxycarbamide  and 
nitrous  gases  (Hantzsch,  1898). 

13.  Interaction  of  dimethylhydroxynitrosocarbamide  and  alkali 
(Hantzsch  and  Sauer,  1898). 

Menke's  reduction  of  fused  alkali  nitrate  by  iron,  and  R&y's  reduc- 
tion of  mercuric  nitrite  by  potassium  cyanide  in  solution,  are  not 
included  in  the  list,  because  both  reductions  are  very  doubtful,  and 
require  confirmation  before  they  can  be  accepted.  In  the  present 
paper,  only  the  original  method  of  preparing  hyponitrites  will  be 
treated  of. 

Preparation  of  Sodivm  HyponUriU  SohUicn  by  the  Reduction  of 
Sodium  Nitrite  with  Sodium  Amalgam. 

Sodium  nitrite  can  be  converted  by  sodium  amalgam  in  the  easiest 
and  quickest  imaginable  way  into  fully  one-sixth  of  its  equivalent  of 
sodium  hyponitrite;  this  remains  in  solution,  and  is  pure  but  for 
the  presence  of  much  sodium  hydroxide.  From  this  solution,  the 
sodium  salt  itself,  as  well  as  silver  hyponitrite,  can  be  at  once  pre- 
pared, nearly  pure  and  with  hardly  any  loss.      The  solution,  if 


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PBEPARATION  BY  SODIUM  OR  POTASSIUM.  97 

caatioosly  neatralisedy  is  also  at  once  fit  for  preparing  lead,  copper, 
mercury,  and  some  other  salts.  The  neutralisation  is  known  to  be 
complete  when  a  little  ot  the  solution  just  ceases  to  give  black  oxide 
when  mixed  with  a  drop  of  a  dilute  solution  of  mercurous  nitrate. 
Others  who  have  tried  this  method,  and  particularly  Hantzsch  and 
Eaufmann,  got  far  less  favourable  results. 

Pure  sodium  nitrite  is  necessary,  but  that  can  now  be  prepared 
very  simply  (this  vol.,  p.  85).  In  order  to  get  as  much  hyponitrite 
as  possible  and  as  little  hydroxylamine,  the  nitrite  must  be  in  con- 
centrated solution ;  three  times  its  weight  of  water  seems  to  be  the 
best  quantity  to  dissolve  it  in  when  operating  in  the  way  to  be 
deecribed.  Using  these  proportions,  there  is  enough  water  to  form, 
with  the  sodium  oxide  produced,  a  solution  of  the  composition 
NaOH+3HsO,  which  is  a  nearly  saturated  solution  of  NaOH,H30  at 
the  mean  temperatura^  In  presence  of  so  much  hydroxide,  the 
water  is  also  quite  saturated  with  hyponitrite,  a  small  quantity  of 
this  salt  even  separating  when  the  solution  is  kept  at  0^  for  a 
time. 

To  reduce  sodium  nitrite  in  cold  concentrated  solution,  2|  atoms  of 
sodium  are  needed,  the  additional  half  atom  being  consumed  in  the 
unavoidable  formation  of  some  nitrogen,  hydroxylamine,  and 
ammonia.  This  accords  well  enough  with  the  statement  in  my  first 
paper,  as  a  first  approximation,  that  not  more  than  4  atoms  are 
active  on  sodium  nUraie,  In  practice,  however,  3  atoms  of  sodium 
should  be  used  in  reducing  sodium  nitrite,  partly  because  it  is  wanted 
afterwards  to  reduce  hydroxylamine,  and  partly  because  it  is  im- 
pmrtant  that  all  the  nitrite  should  be  reduced,  and  this,  notwith- 
standing statements  to  the  contrary,  can  only  be  accomplished  quickly 
in  presence  of  a  good  excess  of  sodium.  The  strength  of  the  amalgam 
18  not  an  essential  point ;  I  have,  however,  found  it  most  con- 
venient to  work  with  a  soft,  solid  amalgam  having  the  composition 
(NaHgg),,  or  23  grams  of  sodium  to  1600  grams  of  mercury. t  The 
temperature,  also,  is  not  of  importance  if  only  the  solution  of  nitrite 
is  concentrated,  and  although  it  may  in  fact  rise  nearly  to  100^  with- 
out harm,  it  is  better  to  follow  my  original  direction  to  keep  the 
flask  in  a  stream  6i  cold  water  during  the  reduction.  It  is,  however, 
preferable  to  cool  it,  particularly  in  warm  weather,  by  means  of  a 
brine  and  ice  bath,  as  then  the  amalgam  can  be  added  much  faster 
without  producing  any  great  evaporation.  The  temperature  of  the 
Bidntion  during  the  reduction  then  ranges,  with  a  convenient  rate  of 

*  Sodium  hydroxide  formB  a  saturated  solation  at  16^  in  its  own  weight  of  water. 
When  coolod,  this  solntion  deposits  large  pointed  prisms  of  the  monhydrate. 

t  Taaatar  erred  in  supposing  that  I  recommended  the  use  of  hard  amalgam, 
and  his  supposed  improvement  of  my  process  is  not  one  in  hct 


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98     DIVERS  :  HTPOKITBITES ;  THEIR  PROPERTIES,  AND  THEIR 

working,  from  5°  to  25^  and  the  time  taken  to  add  23  grams  of 
sodium  need  not  be  more  than  10  minutes. 

From  a  quarter  to  a  half  gram-molecule  i>f  sodium  nitrite  is  a  oon- 
▼enient  quantity  to  work  on,  and  the  solution  is  best  contained  in  a 
360  to  460  C.C.  pear-shaped,  wide  mouthed  flask,  lying  very  obliquely 
in  the  cooling  bath  while  the  amalgam  is  added  by  means  of  a 
spatula.  The  last  fourth  of  the  amalgam  may  be  put  into  the  flask 
as  rapidly  as  it  can  be,  and  the  flask  may  then  be  removed  from  the 
bath.  It  is  kept  actively  rotated  for  10 — 16  minutes,  during  which 
the  temperature  will  rise  to  about  40°  and  then  f  alL  The  solution 
and  mercury  are  next  poured  into  a  narrow  mouthed  stoppered  bottle 
so  as  to  half  fill  it,  the  thick,  aqueous  solution  adhering  to  the  flask 
being  washed  into  the  bottle,  but  the  water  used  should  be  limited  to 
2  or  3  C.C.  if  it  is  desired  to  obtain  the  solid  sodium  salt.  The  whole 
is  now  violently  shaken  for  10  minutes  or  so,  so  as  to  destroy  all  the 
hydrozylamine.  To  ascertain  this,  a  drop  of  the  solution  is  tested  by 
diluting  it  and  adding  a  drop  of  silver  nitrate  solution,  and  a  slight 
excess  of  dilute  nitric  acid ;  there  should  not  be  the  slightest  black 
tint  due  to  silver  reduced  by  hydrozylamine.  No  gas  is  liberated 
during  the  shaking,  but  a  very  strong  odour  of  ammonia  is  developed. 
Strange  to  say,  a  minute  quantity  of  nitrite  is  still  present,  and  it 
seems  almost  impossible  to  entirely  remove  it,  although  it  can  be  so 
far  reduced  by  an  hour's  shaking  of  the  solution  with  the  amalgam 
that  the  acidified  solution  does  not  blue  potassium  iodide  and  stcuroh 
until  it  has  stood  for  about  an  hour. 

On  separating  the  solution  from  the  amalgam  and  exposing  it  in 
a  dish  overnight  over  sulphuric  acid,  under  reduced  pressure,  it  will 
be  free  from  ammonia,  and  is  virtually  a  pure  and  stable  concen- 
trated solution  of  sodium  hyponitrite  and  hydroxide. 

As  here  described,  the  preparation  of  a  solution  of  sodium  hypo- 
nitrite  ready  for  use  is  the  same  as  that  followed  by  me  in  1871  (with 
nitrate),  except  the  important  modification  in  the  manner  of  removing 
the  hydroxylamine.  When  silver  hyponitrite  is  prepared  from  the 
crude  solution,  the  hydroixylMsiine  gets  destroyed  by  silver  oxide^  as 
I  pointed  out  in  the  addendum  to  my  first  paper.  Zom,  as  an 
improvement,  introduced  the  use  of  mercuric  oxide,  on  the  ground 
that  destruction  of  some  silver  hyponitrite  was  thus  avoided,  but 
he  overlooked  the  fact  that  it  is  the  silver  oxide,  just  as  it  is  mer- 
curic oxide^  which  becomes  decomposed,  the  hyponitrite  or  any  other 
add  radide  being  untouched  by  the  hydroxylamine  in  alkaline  solu- 
tion. Whether,  therefore,  mercuric  oxide,  or  silver  nitrate,  or  mer- 
curic nitrate  is  used,  and  the  precipitated  metal  then  separated,  the 
result  is  just  the  same  in  concentrated  alkaline  solutions,  except  that 
the  dropping  in  a  solution  of  the  nitrate  is  more  easy  to  carry  out 


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PREPARATION  BT  SODIUM  OR  POTASSIUM.  99 

thftn  stirring  ap  with  merouric  oxide.  Farther,  where  the  alkaline 
soliiiion  is  very  weak,  the  use  of  mercnry  compounds  ia  not  without 
objeetiony  as  a  little  merourio  oxide  remains  in  solution.  But  whether 
silver  or  mercury  oxide  is  employed,  the  result  ia  unsatisfactory,  for, 
as  Thnm  has  pointed  out,  both  these  oxideSy  in  destroying  the  hydr- 
oxylamine,  regenerate  nitrite.  Not,  however,  that  Thum  himself 
found  this  prevented  him  from  successfully  purifying  the  silver  hypo- 
nitrite  from  nitrite  by  thorough  washing  and  reprecipitation.  Ber- 
thelot  and  Ogier,  Paal  and  Kretschmer,  and  I  myself,  have  not, 
however,  met  with  the  same  success,  as  I  found  it  necessary,  in  order 
to  get  silver  hyponitrite  free  from  all  trace  of  nitrite,  to  begin  by 
pneiidtating  it  in  the  absence  of  nitrite.  Nevertheless,  far  from 
doubt  on  Thum's  statement,  I  believe  his  silver  salt  to  have 
me  of  the  purest  ever  prepared,  from  the  account  he  has  given 
of  the  properties  of  hyponitrous  acid.  No  .one,  however,  will  be 
di^Msed  to  deny  the  superiority  of  sodium  as  a  means  of  removing 
the  hydroxylamine  from  the  solution. 

An  almost  pure  solution  of  sodium  hyponitrite  can  be  conveniently 
got  by  dissolving  the  freshly  prepared,  hydrated,  solid  salt  in  water. 
Sodium  iodide,  or  potassium  iodide  and  the  silver  salt,  will  also  furnish 
a  solution  of  alkali  hyponitrite.  To  get  a  solution  for  precipitating 
purposes,  Thum  proceeded  in  an  indirect  way,  first  preparing  a  solu- 
tkm  6t  hyponitrous  add,  and  then  adding  enough  sodium  hydroxide  to 
make  the  solution  neutral  to  phenolphthalein,  an  effective  but  very 
wasteful  process.  Kirsohner  also,  wanting  a  solution  for  precipitating 
purposes,  used  sodium  chloride  and  silver  hyponitrite,  which,  in 
complex  and  wasteful  way,  he  made  to  yield  a  solution  which  although 
mixed  with  much  chloride  and  nitrate,  was  practically  free  from  silver. 

Sodium  H^panUrite. 

In  1878,  Menke  gave  full  analyses  of  crystals  of  a  stable  salt 
having  the  composition  of  sodium  hyponitrite  containing  GH^O, 
whieh  he  had  prepared  by  deflagrating  in  an  iron  crucible  a  mixture 
of  sodium  nitrate  and  iron  filings,  keeping  the  product  at  a  red  heat 
for  an  hour  in  a  fire  <rf  charcoal  rather  than  of  gas,  boiling  the  mass 
with  water,  filtering  off  iron  oxide,  evaporating,  and  leaving  to 
etystallise.  He  makes  no  reference  in  his  paper  to  the  large  amount 
of  sodium  hydroxide  he  must  have  had  to  deal  with,  although  this 
should  have  seriously  affected  the  procedure.  In  1882,  Zom  sub- 
mitted Menkens  method  to  a  thorough  examination,  but  failed  to  obtain^ 
the  least  trace  of  hyponitrite;  he  found,  however,  that  ferrous 
hydroxide,  acting  on  a  solution  of  sodium  nitrite,  did  produce  sodium 
hyponitrite  (in  solution).    His  suggestion  that  Henke  bad  mistakep 


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100  DIYEBS:  HTPONITRITES ;  THEIR  PROPERTIES,  AND  THEIB 

carbonate  for  hyponitrite  takes  no  account  of  the  fact  that  tlie 
nitrogen  and  water  in  the  salt  were  repeatedly  determined.  It  can 
now,  however,  be  stated  with  certainty  that  Menke's  salt  was  not  the 
sodium  hyponitrite  obtainable  by  reducing  sodium  nitrite  by  sodium 
amalgam  and  water,  for  this  differs  from  it  in  degree  of  hydration, 
stability,  and  in  other  properties. 

D.  H.  Jackson  (Froc,  1893)  described  two  ways  in  which  he  had 
succeeded  in  preparing  sodium  hyponitrite,  but  with  such  difficulty  that 
he  was  deterred  from  investigating  its  properties ;  indeed,  he  merely 
mentions,  in  proof  of  his  success,  that  he  obtained  crystals  which  con* 
tained  the  theoretical  proportion  of  sodium,  but  this  happens  to  be  no 
proof  at  all,  as  sodium  carbonate  has  just  the  same  content  of  sodium  ; 
moreover,  the  hyponitrite  is  a  hydrated  salt  which  cannot  be  ren- 
dered anhydrous  without  some  decomposition,  and  although  of  crystal- 
line texture,  the  salt  can  hardly  be  described  as  occurring  in  crystals. 
Nevertheless,  his  success  in  getting  the  salt  is  not  to  be  doubted* 
One  of  the  methods  he  adopted  was  to  reduce  a  concentrated  solution 
of  sodium  nitrate  by  sodium  amalgam,  evaporate  the  solution  in  a 
vacuum  until  the  salt  crystallised,  and  wash  the  crystals  with  alcohol 
to  free  them  from  sodium  hydroxide.  With  some  modificati<»i,  the 
process  he  followed  is  an  excellent  ona 

To  obtain  sodium  hyponitrite  from  the  somewhat  thick  solution  pre- 
prepared  as  already  described,  it  is  first  passed  through  a  €k>och  asbestos 
filter  well  covered  from  the  air  ;  it  contains  1  mol.  of  sodium  hydroxide 
to  3  mols.  of  water,  and  is  a  saturated  solution  of  the  hydroxide,  whUst 
there  are  about  21^  atoms  of  sodium  present  as  hydroxide  to  1  as 
h3rponitrite.  Cooling  alone  will  cause  the  separation  of  the  hypo- 
nitrite, and  the  solution  readily  loses  water  in  a  vacuum  over  sulphuric 
acid  until  it  retains  only  about  2  mols.  to  1  mol.  sodium  hydroxide, 
when  almost  the  whole  of  the  sodium  hyponitrite  will  have  separated  ; 
at  25 — 30^,  this  will  happen  in  about  40  hours,  the  salt  separating  as 
minute,  crystalline  granules,  some  of  which  adhere  to  the  walls  of  the 
dish,  but  most  of  them  being  deposited  as  a  thick  crust  on  the 
surface  of  the  solution.  Below  15^,  the  mother  liquor  readily  deposits 
crystals  of  the  monhydrate  of  sodium  hydroxide,  and  as  evaporation 
is  slower  in  the  cold,  it  is  better,  for  both  reasons,  to  conduct  the 
operation  in  a  warm  room. 

The  only  effective  way  of  separating  the  salt  from  its  viscid  mother 
liquor  is  by  the  pump  and  a  Gooch  crucible  unlined  with  asbestos ; 
draining  on  a  tile  is  impossible.  In  the  same  apparatus,  it  is  washed 
with  absolute  alcohol  and  then  transferred  to  a  basin  and  gently 
triturated  with  fresh  portions  of  alcohol  until  all  the  sodium  hydroxide 
has  been  removed.  If  now  drained  on  a  good  tile,  it  is  the  nearly 
pure  hydrated  salt,  but  very  unstable,  losing  both  water  and  nitrous 


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PBEPABATION  BY  SODIUM  OB  P0TASSIX7M.  101 

oxide,  and  consequently  becoming  contaminated  again  with  sodium 
hydroxide ;  if,  however,  it  is  promptly  dried  in  a  vacuum  desiccator, 
it  becomes  anhydrous  before  it  has  undergone  much  decomposition, 
and  is  then  quite  stable  in  dry  air.  The  amount  of  the  hydrated 
sodium  hyponitrite  should  be  quite  one-sixth  of  the  calculated  quantity, 
and  the  mother  liquor  wUl  then  be  too  poor  in  hyponitrite  to  be  used 
as  a  source  of  sUver  hyponitrite. 

A  modification  of  the  method,  which  gives  an  equally  good  yield,  is 
to  precipitate  the  salt  by  absolute  alcohol  instead  of  evaporating ;  the 
only  precaution  necessary  is  to  prevent,  as  far  as  possible,  the  salt  from 
becoming  attached  to  the  walls  of  the  vessel.  A  large  quantity  of 
alcohol  is  required,  because  of  the  very  large  proportion  of  sodium 
hydroxide  which  is  present.  A  few  drops  of  the  solution  are  added  to 
the  alcohol  in  a  flask  and  at  once  violently  shaken  with  it  until  the 
hyponitrite  has  completely  solidified ;  then  gradually  the  rest  of  the  solu- 
tion is  poured  in  with  very  active  agitation.  If  abundance  of  alcohol 
is  used  from  the  first,  with  thorough  mixing,  very  little  of  the  salt  will 
remain  in  solution  and  very  little  adhere  to  the  flask ;  with  less 
alcohol  at  first,  a  notable  quantity  of  the  salt  is  lost  by  being  kept  in 
solution,  for  although  it  is  afterwards  slowly  deposited,  it  is  not  then 
in  a  serviceable  condition,  and  much  salt  is  liable  to  adhere  to  the 
flask,  which  can,  indeed,  be  dissolved  out  in  water,  and  be  reprecipitated 
by  alcohol,  but  only  with  very  great  loss. 

The  action  of  sodium  chloride  on  silver  hyponitrite  (see  p.  106)  is 
complex  and  quite  unsuitable  for  the  preparation  of  a  solution  of 
pore  sodium  hyponitrite.  Nevertheless,  such  a  solution,  charged  as 
it  is  with  sodium  chloride,  and  containing,  besides,  some  silver 
hyponitrite  dissolved  in  it,  deposits  sodium  hyponitrite  when  mixed 
with  much  absolute  alcohol,  and  this  coDstitutes  Jackson's  second 
method  of  getting  the  salt  j  it  always,  however,  contains  a  little 
chloride  mixed  with  it. 

The  granular  form  of  sodium  hyponitrite  is  most  marked  in  it  when 
it  has  been  separated  from  a  highly  concentrated  solution  of  sodium 
hydroxide ;  when  it  is  redissolved  in  a  very  little  water  and  the  solu- 
tion rapidly  evaporated  in  an  exhausted  desiccator,  the  salt  separates 
as  an  inmost  structureless  membrane  on  the  surface,  and  there  readily 
becomes  opaque  and  apparently  anhydrous.  In  the  ordinary  desiccator, 
a  finely  granulated  crdst  forms.  I  have  never  obtained  it  in  crystals. 
The  Bait,  when  quite  freshly  prepared,  has  an  exceedingly  mild,  alkaline 
taste. 

The  attempts  to  determine  the  degree  of  hydration  of  the  salt  have 
been  unsatisfactory  because  of  its  instability,  but  they  point  to  the 
formula  (NaON),-l-5HsO.  That  formula  requires  23*47  per  cent, 
sodium,  whflst  analysis  of  the  salt  weighed  as  soon  as  it  was  almost 

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102   DIVERS:  UrPONITRITBS ;  THEIR  PROPERTIES,    AND  THEIR 

free  from  alcohol,  gave  23*66  per  cent.  In  place  of  30'61  per  cent,  for 
the  hyponitiite  ion,  28*10  per  cent,  was  obtained  by  dissolving  the  salt 
in  water  and  precipitating  with  silver  nitrate,  a  deficiency  fairly 
attributable  to  decomposition  before  the  silver  nitrite  could  be  added ; 
for,  as  proved  by  Zom,  this  way  of  estimating  hyponitrous  acid  is 
accurate.  Loss  of  weight  in  the  vacuum  desiccator  gave  44*91  per 
cent.,  whilst  the  calculated  quantity  of  water  is  46*92  per  cent.,  but 
the  difference  is  easily  accounted  for  as  due  to  loss  of  nitrous  oxide, 
and,  indeed,  would  be  even  greater  but  for  the  fact  that  this  loss 
involves  fixation  of  water  by  sodium  oxide. 

The  anhydrous  salt,  somewhat  decomposed,  is  non-coherent  and 
opaque,  and  in  appearance  much  like  that  of  magnuia  alba ;  heat  is 
evolved  when  it  dissolves  in  water,  and  it  is  insoluble  in  alcohoL  The  an- 
hydrous salt  only  slowly  takes  up  water  from  a  solution  of  sodium  hypo- 
nitrite.  Heated  in  a  closely-covered  vessel,  it  yields  nitrogen  and  sodium 
oxide  mixed  with  some  nitrate,  3(NaON)2  »  2Ns  +  2Na,0  +  2NaN0,. 
The  salt  bears  a  heat  of  300°  without  decomposing,  and  then  melts  and 
effervesces ;  glass,  platinum,  and  even  silver  are  freely  attacked  by  the 
fused  mass,  and  the  product  hisses  when  water  is  added  to  it.  Sodium 
hydroxide  and  nitrite  are  the  solid  products  when  the  hydrated  salt  is 
quickly  heated,  and  nitrous  oxide,  as  well  as  nitrogen,  is  given  otL 
Strong  sulphuric  acid  decomposes  the  salt,  with  production  of  odour- 
less, white  vapours,  and  does  not  form  nitrosylsulphate  if  the  sodium 
salt  is  pure. 

The  salt,  or  a  fairly  concentrated  solution  of  it,  effervesces  with  a 
dilute  acid  like  a  carbonate.  The  solution,  with  the  respective  re- 
agents, gives  a  precipitate  of  calcium  hyponitrite  and  of  most  other 
hyponitrites  at  once.  It  dissolves  a  little  silver  hyponitrite  and  decom- 
poses silver  chloride  (see  the  account  of  silver  hyponitritei  p,  106). 
Dry  sodium  hyponitrite  is  not  decomposed  by  carbon  diaxide»  and, 
since  the  hydrated  or  dissolved  salt  partly  decomposes  by  interaction 
with  the  water,  its  power  of  fixing  carbon  dioxide  does  not  indicate 
that  it  is  directly  decomposable  by  that  substance.  The  solution, 
when  boiled,  decomposes  moderately  fast  into  hydroxide  and  nitrous 
oxide.  If  allowed  to  stand  for  a  day,  a  trace  of  nitrite  is  formed 
(see  p.  114). 

PataaHum  HyponUriie;  PokuHum  Amalgam. 

The  preparation  of  a  solution  of  potassium  hyponitrite  is  throughoat 
like  that  of  a  solution  of  the  sodium  salt.  It  is  only  necessary, 
therefore^  to  say  something  concerning  the  potassium  ^^n^ftlgam  which 
is  required,  concerning  which  as  a  reagent  little  or  nothing  has  been 
published. 

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PREPABATION  BT  SODIUM  OB  POTASSIUM.  103 

Merely  for  convenience  in  working,  tlie  composition  of  the  potasdiim 
amalgam  shonld  oorrespond  pretty  cloflely,  in  parte  by  weight,  to  that 
reecNnmended  for  the  sodium  amalgam,  namely,  (Hgi^K)^,  or  2800  of 
mercury  to  39  of  potassium,  this  being  the  weakest  anudgam  that  is 
solid,  a  pasty  amalgam  like  that  of  sodium  not  being  obtainable. 
Although  it  crystallises  in  simple  cubes,  often  very  large,  which  are  so 
sharp  angled  tiiat  they  can  hardly  be  introduced  into  a  flask  without 
fracturing  it,  these  crystals  are  very  easily  crushed,  in  a  porcelain 
mortar,  and  are  then  in  a  state  quite  convenient  for  use.  Sodium  or 
potaflsinm  amalgam  not  stronger  than  here  recommended  (1  kilo,  of 
mercury  to  14  grams  of  alkali  metal)  is  particularly  easy  to  prepare  in 
Draper's  way,  that  is,  by  melting  the  sodium  or  potassium  under  solid 
paraffin  and  adding  the  mercury  to  it,  at  first  very  gradually.  The 
operation  can  be  performed  on  the  open  table.  In  spite  of  the  fact 
that  more  heat  is  evolved,  according  to  Berthelot's  numbers,  the  action 
is  less  violent  in  preparing  potassium  amalgam  than  it  is  in  the  case 
of  sodium  amalgam.  Potassium,  also,  nearly  always  requires  to  be 
well  stirred  with  a  glass  rod  to  bring  about  its  first  contact  with  the 
mercury  under  the  paraffin;*  sodium  never  does.  When  all  the 
mercury  has  been  added,  either  amalgam  requires  good  stirring  in 
order  to  dissolve  all  lumps,  and  should  again  be  stirred  when 
solidifying,  in  order  to  disturb  crystallisation  as  much  as  possible. 
The  specific  gravity  of  the  paraffin  is  about  the  same  as  that  of 
potassium,  but  paraffin  expands  so  very  greatly  in  melting  that  the  po- 
tassium readily  sinks  in  it  when  it  is  in  the  liquid  state.  Muhlhaeuser, 
many  years  ago,  melted  sodium  under  petroleum  and  then  added  the 
mercury  to  it,  and,  in  recent  years,  Nef  has^  recommended  the  use  of 
toluene,  which  boils  freely  by  the  heat  produced  in  the  union  of  the 
metals.  But  toluene  could  hardly  be  used  in  making  potassium  amalgam, 
because  of  its  specific  gravity. 

A  highly  concentrated  solution  of  potassium  hyponitrite  and 
hydroxide  having  been  prepared,  the  hyponitrite  can  be  precipitated 
1^  absolute  alcohol,  but  only  very  incompletely,  and  some  of  what  is 
precipitated  is  afterwards  dissolved  away  in  washing  it  with  more 
aloolu^  The  preparation  of  this  salt  is,  therefore,  less  satisfactory 
than  that  of  the  sodium  salt. 

Another  way  of  making  potassium  hyponitrite  is  to  decompose  sUver 
hyponitrite  with  exactly  the  right  quantity  of  solution  of  potassium 
iodida  By  rapid  evaporation  under  reduced  pressure,  the  solution  can 
be  eoncentrated,  although  with  partial  decomposition,  preparatory  to 
treatiBg  it  with  absolute  alcohol,  and  it  can  even  be  dried  up,  so  as  to 

*  This  is  probably  dne  to  the  foot  that  the  potassiom  presses  but  lightly  upon 
the  mereniy  on  account  of  its  specific  gravity  not  greatly  exceeding  that  of  the 
paraJBn,  aad  not  beeanse  of  any  chemical  difference. 

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104    DIVEBS  :  HTP0NITBITS8 ;  THEIR  PROPEBTIES,  AND  THS&R 

yield  the  impure  solid  salt.  The  cold  of  evaporation  in  a  vacanm  has 
sometimes  caused  the  separation  from  the  concentrated  solution  of 
hydrated  crystals,  which,  however,  melt  when  placed  on  filter  paper ; 
otherwise,  the  salt  is  obtained  anhydrous  in  minute,  prismatic  crystals. 
The  salt  decomposes  more  rapidly  than  the  sodium  salt,  but  is  stable 
when  quite  dry.  It  is  soluble  in  90  per  cent,  spirit,  and  slightly  even 
in  absolute  alcohol.  Its  aqueous  or  alcoholic  solution  yields  silver 
hyponitrite  with  sUver  nitrate,  dissolves  silver  hyponitrite  to  some 
extent,  and  in  other  respects  behaves  like  one  of  sodium  hyponitrite. 
It  has  not  been  obtained  sufficiently  undecomposed  to  be  fit  for 
quantitative  analysis. 

PfBparaiion  of  Silver  ffypamtrite. 

The  hyponitrites  were  discovered  through  the  production  of  the 
silver  salt,  and  since  that  discovery  this  hyponitrite  has  been  prepared 
and  redescribed  by  many  chemists ;  all  deviations  from  the  account  I 
first  gave  of  it  are,  however,  incorrect,  and  the  only  additional  observa- 
tions that  have  been  made  are  that  it  can  be  obtained  in  a  purer  state 
than  I  got  it  at  first,  and  that  it  gives  off  nitric  peroxide  when  heated. 
The  very  poor  success  in  obtaining  it  in  satisfactory  quantity  in  recent 
years  is  remarkable  (see  p.  97) ;  this  seems  to  be  due  to  erroneous 
methods  of  procedure,  either  in  reducing  the  nitrite  or  in  converting 
the  sodium  hyponitrite  into  the  silver  salt. 

The  concentrated  solution  of  sodium  hyponitrite  and  hydroxide, 
already  described,  is  diluted  and  mixed  with  just  sufficient  silver 
sulphate  or  silver  nitrate,  dissolved  in  much  water,  to  precipitate  the 
hyponitrite ;  for  it  is  unnecessary  to  neutralise  the  sodium  hydroxide. 
(Neutralisation  can,  indeed,  precede  precipitation,  if  desired,  as  in  pre- 
paring mercury  and  other  hyponitrites,  but  in  the  case  of  the  silver  salt 
it  is  quite  unnecessary,  and  there  is  a  risk  of  loss  of  hyponitrite.)  Silver 
sulphate  should  be  used  if  it  is  essential  to  exclude  nitrate  from  the  silver 
hypom'trite ;  for,  as  will  be  shown,  washing  and  reprecipitating  are  but 
imperfect  means  of  purifying  the  precipitate.  Supposing  a  half  gram- 
molecule  of  sodium  nitrite  to  have  been  reduced,  the  alkaline  solution, 
diluted  to  three  times  its  volumeor  more,  is  mixed  with  13  grams  of  silver 
sulphate  or  14  grams  of  silvernitrate  dissolved  in  about3  litres  of  water, 
and  the  mixture  stirred  vigorously  at  once  and  continuously  for  6 
minutes,  in  order  to  convert  the  silver  oxide  into  silver  hyponitrite. 
After  the  precipitate  has  nearly  all  subsided,  the  turbid  liquor,  if 
bright  yellow  rather  than  brownish,  is  decanted  and  more  silver  solution 
added  to  it  until,  after  stirring  well,  some  brown  silver  oxide  remains, 
when  the  whole  is  poured  back  and  stirred  up  with  the  main  pre- 
cipitate, and  then  left  to  settle.    Good  daylight  is  almost  essential 

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PB£PABATION  BT  SODIUM  OR  POTASSIUM.  105 

for  jadging  the  colour  of  the  precipitate  when  finishing,  bat  the 
preci{Atate  should  not  be  exposed  to  light  more  than  is  absolutely 
neceesary. 

After  washing  somewhat  by  decantation,  the  precipitate  is  stirred 
up  with  successiye  portions  of  highly  dilute  sulphuric  acid  (3  or  4  per 
mille)  until  this  fails  to  become  fully  neutralised,  and  shows,  there- 
fore, when  poured  off  and  mixed  with  a  drop  of  sodium  carbonate,  a 
slight  yellow  opalescence  due  to  silver  hyponitrite.  The  precipitate, 
after  being  washed  with  water  by  decantation  until  the  washings  no 
longer  contain  sulphate,  is  stirred  up  with  water  containing  a  trace  of 
sodium  carbonate,  and,  finally,  again  washed  with  water.  It  is  then 
collected  on  a  filter  and  dried  in  the  dark  in  a  vacuum.  When  thus 
dried,  it  may  be  heated  for  a  time  to  100°  in  dry  air  without  change 
and  become  still  drier.  It  is  now  usually  as  pure  as  it  is  possible  to 
get  it.  As,  however,  the  operations  are  not  always  so  perfectly 
carried  out  as  to  ensure  this  degree  of  purity,  it  is  desirable  some- 
times to  submit  the  salt  to  further  treatment,  preferably  before  it 
has  been  dried.  In  that  case,  it  is  dissolved,  in  portions  at  a  time, 
in  3  per  mille  ice  cold  dilute  sulphuric  acid,  and  is  either  ex- 
peditiously filtered,  if  necessary,  into  some  sodium  carbonate  solution, 
or,  if  not,  is  at  once  made  alkaline  with  sodium  carbonate.  The  re- 
predpitated  salt  b  then  treated  with  sulphuric  acid  and  washed  in 
exactly  the  same  manner  as  the  original  precipitate.  Even  after 
reprecipitation,  the  silver  hyponitrite  obtained  from  34*5  grams  of 
sodium  nitrite  will  weigh  about  11  grams. 

Hie  process  for  preparing  silver  hyponitrite  just  given  differs  from 
that  contained  in  my  first  paper  in  not  neutralising  the  sodium 
hydroxide  with  acetic  add,  in  taking  silver  sulphate  instead  of 
nitrate,  sulphuric  acid  in  place  of  nitric  acid,  and  sodium  carbonate 
in  place  of  ammonia,  and  in  some  minor  details.  The  use  of  sulphuric 
acid  is  not  new,  that  acid  having  been  first  used  by  van  der  Flaats, 
but  the  motive  for  the  change  is  new  and  has  been  already  given. 
Cold  dilute  sulphuric  acid  is  not  in  the  least  less  active  than  nitric 
acid  in  decomposing  silver  hyponitrite ;  in  fact,  unless  very  dilute,  it 
is  more  active  in  consequence  of  silver  sulphate  crystallising  out. 
Sodium  carbonate  (used  by  Haga  and  me  in  1884,  Trans.,  46,  78) 
is  to  be  preferred  to  ammonia  for  precipitating  the  salt,  as  being 
more  sensitive,  and  because  the  last  trace  of  ammonia  is  dificult  to 
wash  out  of  the  silver  salt  (as  Hantzsch  and  Kaufmann  found, 
see  p.  114).  It  is  easy  to  ensure  absence  of  all  silver  carbonate, 
along  with  complete  precipitation  of  the  hyponitrite,  because  of  the 
solubility  of  the  carbonate  in  the  excess  of  carbon  dioxide  always 
present  in  the  solution. 


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106  DIVERS  :  HTP0MITRITB8  ;  THEIR  PEOPEBTIES,  AND  THEIR 


PropertUs  qf  JSilver  HypanUrite. 

Silver  hyponitrite  is  bright  yellow,  and  when  pale  in  colour  it 
generally  contains  a  trace  of  ammonia  or  loosely  combined  silver 
oxide.  If  along  with  such  impurity  there  is  also  black  silver  sub- 
oxide, the  colour  becomes  dull  greyish-yellow,  but  when  other 
impurities  are  absent,  the  presence  of  a  little  black  oxide  renders  it 
somewhat  bright  green,  as  seen  principally  in  the  crude  salt  prepared 
by  the  hydroxyamidosulphonate  method.  The  difference  in  colour 
observed  has  even  suggested  the  possibility  of  the  existence  of  different 
modifications,  but  there  is  really  nothing  to  support  this  notion. 

If  precipitated  from  strongly  alkaline  solution,  or  from  concen- 
trated solutions  of  the  sodium  salt  and  silver  nitrate,  or  in  rubbing 
the  calcium  salt  with  strong  solution  of  silver  nitrate,  silver  hypo- 
nitrite  is  dense,  but  when  precipitated  by  neutralising  its  solution  in 
dilute  acid,  it  is  flocculent  and  bulky.  When  deposited  from  its 
ammoniacal  solution  through  evaporation  or  large  dilution  with  water, 
it  is  crystalline  (Kirschner ;  but  also  see  Faal  and  Kretschmer). 

It  is  slightly  more  soluble  in  water  than  silver  chloride,  and  is 
dissolved  by  very  dilute  nitric  or  sulphuric  acid,  so  as  to  be  recover- 
able on  quickly  neutralising  the  acid.  The  nitric  acid  required  to 
dissolve  it  is  considerable,  being  about  3  equivalents.  The  sulphuric 
acid  solution  very  soon  deposits  silver  sulphate.  Acetic  acid 
dissolves  it  only  very  slightly  in  the  cold ;  phosphoric  acid  dissolves 
it,  but  not  very  freely.  It  is  dissolved  by  anunonia  solution,  but  only 
sparingly  when  this  is  very  dilute,  and  the  same  salt  can  be  recovered 
either  by  neutralising  or  dissipating  the  ammonia.  It  is  also  soluble 
in  ammonium  carbonate  solution,  and  very  slightly  in  ammonium 
nitrate  solution.  Qf  particular  interest  is  its  solubility  to  a  slight 
extent  in  hyponitrous  acid  solution,  and  to  a  greater  degree  in 
solution  of  an  alkali  hyponitrite. 

It  is  readily  oxidised  by  strong  nitric  add.  Strong  sulphuric  aoid 
acts  energetically,  the  heat  of  reaction  being  itself  quite  sufficient  to 
decompose  some  of  the  salt,  a  fact  which  accounts  for  the  production 
of  some  nitric  peroxide  and  nitrosyl  sulphate  (see  effects  of  heating, 
p.  108).  It  is  not  decomposed  by  a  cold  solution  of  sodium  carbonate, 
or  by  one  of  Sodium  hydroxide  if  it  is  weak.  It  is  fully  decomposed 
by  its  equivalent  of  potassium  iodide  in  solution,  but  only  imperfectly 
by  a  solution  of  sodium  chloride,  if  the  latter  is  not  in  considerable 
excess.  When  a  solution  of  sodium  chloride  is  shaken  with  excess  of 
undried  silver  hyponitrite,  decomposition  ceases  when  the  two  sodiuxa 
salts  in  the  solution  are  in  the  proportion  of  18  eq.  of  chloride  to 
25  eq.  of  hyponitrite,  or,  by  weight,  4  of  chloride  to  5  of  anhydrous 


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PRBPABATION    BT  SODIUM  OB  POTASSIUM.  107 

byponitrite.  Absolute  alcohol  in  large  excess  effects  a  partial 
separation  of  the  two  sodium  salts,  as  already  described. 

Silver  hyponitrite  in  the  moist  state  is  not  entirely  stable,  for  it 
daeompoeee  even  at  the  ordinary  temperature,  although  exceedingly 
slowly  ;  light  and  heat  qdeken  the  change,  the  former  modifying  it 
to  some  extent.  The  decomposition  is  made  evident  by  the  salt  losing 
ItB  bright  oolomr,  by  its  answering  to  the  iodide  and  starch  test  for  a 
nitrite^  and  by  its  yielding  up  to  water  more  silver  salt  (not  nitrite, 
but  nitrate  apparently)  than  its  own  very  slight  solability  would 
aecount  for.  The  salt  may  be  washed  with  boiling  water,  or  even  be 
boiled  with  water,  without  any  very  apparent  result,  but  oontinuous 
boiling  not  only  has  marked  effect  in  decomposing  it,  but  an  action 
which  grows  in  intensity,  even  though  the  water  is  frequently  re- 
I^aeed.  The  water  is  found  to  contain  silver  nitrate,  whilst  the  solid 
salt  gives  the  reaction  for  nitrite.  Masses  of  moist  precipitate  retain 
their  eoloor  outside  while  drying  in  a  thermostat^  but  beM>me  greyish 
inside.  Silver  hyponitrite  dissolved  in  a  solution  of  sodium  or  potassium 
hypcmitrite  decomposes  on  standing,  and  very  quickly  on  boiling, 
reduced  silver  being  deposited  and  sodium  nitrate  formed  in  solution. 

Blight  diffused  light  causes  enough  change  in  a  few  hours — bright 
sunlight  in  a  few  minutes — ^to  allow  of  nitrite  being  detected.  The 
colour  ohange  caused  by  light  has  been  variously  described;  as  a 
matter  of  fact,  in  the  sufficiently  pure  salt  under  water,  it  is  such 
that  tlie  bright  yellow  hyponitrite  becomes  covered  with  a  somewhat 
bright  Inown,  floceulent  substance,  very  like  silver  oxide,  whicb,  per- 
hi^B,  it  IB ;  the  blaekening  or  greying,  which  has  been  observed  by 
others  to  be  cansed  by  light,  must  have  been  due  to  impurities, 
although  time,  as  just  described,  brings  about  a  greying  of  the  salt. 
Silver  hyponitrite  is  least  sensitive  to  light  when  dry  and  exposed  to 
dry  air.  Hie  main  change  which  occurs  in  the  moist  salt,  slight  as  it 
ifly  18  evidently  similar  to  that  caused  by  heat.  The  salt  prepared  by 
the  hydroxyamidoBulphonate  method  generally  shows  an  unreal 
stability,  due  apparently  to  presence  in  it  of  a  trace  of  sulphite,  as 
will  be  explained  when  the  properties  of  a  hyponitrous  acid  solution 
are  treated  of;  for,  in  that  connection,  it  has  to  be  taken  into  con- 
sideration that,  like  many  other  precipitated  substances,  silver 
hyponitrite  ia  difficult  to  obtain  of  high  purity.  The  very  slight 
atmoqpherie  oxidation  of  moist  silver  hyponitrite,  described  by  Haga 
and  me  (Trans.,  1884, 46,  p.  78)  I  now  regard  as  being,  not  the  oxidation 
of  the  salt  itself,  but  of  nitric  oxide  produced  by  the  very  slowly 
deeompoeing  salty  whieh  is  then  retained  as  nitrate  and  nitrite  in  the 
salt ;  the  result  would  be  the  same  as  if  the  wit  itself  were  oxidised. 


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108   DIVERS:  HTPONITRITES ;  TREIB  PROPERTIES,  AND  TBBtR 


Effects  of  Healing  Stiver  Hyponii/riU. 

In  my  first  paper,  it  is  stated  that  silver  hyponitrite  is  decomposed 
by  a  moderate  heat  into  nitric  oxide,  metallic  silyer,  and  a  little  silver 
nitrate — ^in  this  respect  resembling  silver  nitrite,  and  that  it  does  not 
fuse  or  exhibit  any  other  change  except  that  from  a  bright  yellow  to  a 
silver-white  colour.  That  is  still  a  correct  statement,  so  far  as  it 
goes,  but  it  is  imperfect.  In  1887»  van  der  Plaats  stated  that  silver 
hyponitrite  decomposes  explosively  when  heated ;  presumably  his 
preparation  contained  acetate.  Thum,  who,  in  1893,  rightly  denied 
its  explosive  character,  observed  that,  in  decomposing  by  heat,  the 
bright  yellow  salt  becomes  dark  brown  before  assuming  the  white 
colour  of  silver,  while  Elirschner  found  (1898)  that  the  salt  became 
temporarily  black.  Thum's  observation  was  due,  I  think,  to  the  very 
dense  red,  almost  opaque,  hot  nitric  peroxide  which  then  poors 
forth,  and  through  which  at  times  the  solid  mass  does  look  very  dark. 
SLirsohner's  observation  may  be  due  also  to  this  cause,  or  to  his  hypo- 
nitrite having  contained  sulphite.  However  this  may  be,  the  salt 
decomposes  with  only  the  change  of  colour  I  have  described,  and  in  a 
lump  of  the  precipitate  the  change  can  be  followed  by  the  change  in 
position  of  the  sharp  boundary  line  between  the  bright  yellow  salt 
and  the  bright  white  metal,  just  as  it  can  be  followed  in  calcium 
oxalate  decomposing  by  heat ;  there  is  no  brown  or  black  intermediate 
stage.  Thum  seems  to  have  found  no  silver  nitrate,  but  observed  the 
production  of  dense  red  fumes  even  when  the  salt  was  heated  in  an 
atmosphere  of  carbon  dioxide,  and  at  a  temperature  not  much 
(f)  above  100^.  From  the  important  observation  of  the  generation  of 
nitric  peroxide,  he  concluded  that  the  decomposition  of  silver  hypo- 
nitrite by  heat  is  probably  into  silver,  nitrogen,  and  nitric  peroxide. 
I  had,  of  course,  seen,  in  my  early  work,  the  production  of  red  fumes, 
but  had  attributed  this  to  the  nitric  oxide  meeting  the  air,  and  to  the 
decomposition  at  a  higher  temperature  of  the  silver  nitrate  which  had 
been  formed.  The  further  study  of  the  decomposition  which  I  have 
made  has  proved  that  metallic  silver,  silver  nitrate,  nitric  peroxide, 
nitric  oxide,  nitrogen,  and  possibly  a  trace  of  nitrite  are  always  produced. 

Having  assured  myself  that  nitric  peroxide,  as  well  as  nitric  oxide, 
is  evolved  by  silver  hyponitrite  when  heated,  I  exposed  some  to  heat 
in  a  rapid  current  of  carbon  dioidde,  in  order  to  sweep  away  as  fast 
as  I  could  the  nitric  peroxide  that  was  produced ;  for  the  production 
of  nitric  peroidde  may  sufficiently  account  for  that  of  silver  nitrate 
secondarily.  The  nitric  peroxide  and  the  metallic  silver  could  give 
the  nitrate  (Divers  and  Shimidzu,  Trans.,  1885,  47, 630),  but  it  seems 
improbable  that  these  two  substances  being  produced  would  then 

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PREPARATION  BT  SODIUM  OR  POTASSIUM.  109 

immediately  interact  at  the  same  temperature.  There  is,  however,  no 
reason  why  the  nitric  peroxide  of  the  decomposed  part  of  the  salt 
should  not  act  on  the  undecompoeed  portion  and  thus  produce  nitrate, 
such  interaction  readily  taking  place.  My  experiment  recorded  above 
was  instituted  to  see  whether  I  could  not  almost  prevent  the  forma- 
tion of  nitrate.  The  attempt  failed,  for  I  found  silver  nitrate  in  the 
residue  equivalent  to  as  much  as  ^th  of  the  total  silver,  but  this 
result  does  not  disprove  that  the  nitrate  really  is  formed  in  the  way 
suggested. 

The  nature  and  composition  of  the  gaseous  products  were  ascertained 
by  heating  the  salt  in  a  vacuum.  The  quantity  of  salt  taken  was  in 
each  experiment  so  proportioned  to  the  capacity  of  the  little  flask  or 
bulb  in  which  it  was  heated  that  the  volume  of  the  gases  at  the 
common  temperature  and  pressure  should  be  a  little  less  than  the 
capacity  of  the  bulb.  The  air  was  removed  from  the  bulb  holding 
the  salt  by  means  of  the  mercury  pump,  while  the  bulb  was  kept  in 
boiling  water  to  ensure  the  dryness  of  the  salt.  When  exhausted, 
the  bulb  was  sealed  off,  and  the  silver  hyponitrite  decomposed  by 
heating  the  bulb  in  a  bath.  Thus  heated  in  the  absence  of  air  and 
moisture,  the  salt  exhibits  scarcely  any  change  below  140°,  and  only 
slow  decomposition  between  140°  and  160°,  but  above  these  tem- 
peratures the  change  is  soon  complete.  The  metallic  silver  is  slightly 
caked  together,  presumably  by  the  silver  nitrate,  and  the  gases  are 
faintly  red  between  140°  and  150°,  and  orange-red  at  160°  and  above. 
On  allowing  the  vessel  to  cool,  the  gases  become  colourless,  but  regain 
their  colour  just  as  before  when  the  vessel  is  again  heated,  and  these 
changes  can  be  repeated  any  number  of  times. 

To  examine  the  contents  of  the  bulb  when  cold,  its  point  was 
broken  off  under  water,  and  the  small  rise  of  water  into  the  neck  of 
the  bulb  marked ;  then  the  bulb  was  transferred  to  a  small  trough  of 
strong  solution  of  sodium  sulphite  in  order  to  absorb  the  nitric  oxide 
(this  vol.,  p.  82).  After  an  hour  or  longer,  the  residual  gas  was 
examined  and  measured  by  bringing  the  bulb  mouth  upwards,  testing 
the  gas  as  to  odour  and  power  to  support  combustion«  and  then  filling  it 
with  water  from  a  burette  up  to  the  mark  already  made,  and  afterwards 
to  the  mouth  in  order  to  learn  the  volumes  of  the  gases  when  corrected 
for  temperature  and  pressure.  The  volumes  could  be  only  approxi- 
mately measured  in  this  way,  but  quite  well  enough  for  the  purpose. 
1%e  metallic  silver  was  weighed,  and  from  its  weight  and  that  of  the 
hyponitrite,  that  of  the  silver  nitrate  became  known.  In  one  experi- 
ment, the  bulb  was  at  once  freely  opened  to  the  air,  and  the  gases 
rapidly  blown  out ;  in  this  way,  the  nitric  oxide  showed  its  presence 
by  reddening  in  the  air,  and  both  the  silver  and  the  silver  nitrate  were 
directly  determined. 

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110  DIVERS  :  HYPONITBITES ;  THEIR  PROPERTIES,  AND  THEIR 

These  experiments  established  the  production  of  nitrogen,  as  well 
as  that  of  the  other  substances,  and  the  non-production  of  any  appre- 
ciable quantity  of  nitrous  oxide.  The  quantitative  results  were  that, 
when  the  decomposition  is  slowly  effected^  as  between  140^  and  160^, 
silver  hyponitrite  yields  about  27  per  cent,  of  its  nitrogen  in  the  free 
state,  and  about  20  per  cent,  when  the  decomposition  is  rapidly 
accomplished  at  higher  temperatures.  The  silver  nitrate  was  formed 
in  quantities  corresponding  with  those  of  the  nitrogen,  according  to 
the  equation  d(AgON)2»4Ag  +  2AgN03  +  2N3,  but  that,  of  course, 
proved  nothing,  since  the  whole  of  the  nitrate  might  have  been 
formed  by  the  nitric  peroxide  during  the  cooling,  as  certainly  much 
of  it  must  have  been.  On  the  other  hand,  the  limited  quantities  of 
nitrogen  generated  gives  full  proof  that  much  nitric  oxide  is  either 
primarily  formed  or  comes  from  interaction  between  hyponitrite  and 
pero3dde,  besides  what  undoubtedly  comes  from  the  interaction  of  the 
nitric  peroxide  and  metallic  silver  during  the  cooling.  Were  none  of 
the  nitrogen  of  the  salt  to  become  nitric  oidde,  the  free  nitrogen 
would  be  half  of  the  total  nitrogen,  instead  of  only  three-  or  four- 
fifteenths  as  found. 

From  the  facts  observed,  it  seems  to  me  to  be  highly  probable  that 
silver  hyponitrite  decomposes  into  silver,  nitrogen,  and  nitric  peroxide, 
according  to  the  equation  2(AgON)2e4Ag  +  N2  +  2NOs,  and  that 
interaction  then  occurs  between  the  hyponitrite  not  yet  decomposed 
andsomeof thenitricpero3dde, thus :  (AgON)^  +  iNO^  «  2AgN03  +  4NO, 
and,  therefore,  that  the  decomposition  of  silver  hyponitrite  into  silver 
and  nitric  oxide  does  not  occur  directly. 

It  remains  to  explain  the  absorption  and  regeneration  of  nitric 
peroxide  by  cooling  and  heating  the  gases  in  contact  with  the  solid 
residue  of  the  decomposed  hyponitrite.  The  interaction  of  silver  and 
nitric  peroxide  in  the  cold,  already  referred  to,  explains  the  disap- 
pearance of  the  nitric  peroxide,  half  of  its  nitrogen  becoming  nitrate 
and  half  nitric  oxide.  The  regeneration  of  nitric  peroxide  at  such 
low  temperatures  as  those  in  the  neighbourhood  of  150°  is  explained 
by  experiments  of  mine  recorded  in  a  separate  note  (this  vol.,  p.  83). 
The  silver  nitrate  and  nitric  oxide  interact  to  produce  nitric  peroxide, 
andatfirst  nitrite,  but  ultimately  silveritBelf,AgNOs  +  NO  »  Ag  +  2NO2.  • 

As  to  the  ExUtmice  qf  Silver  Nitrit<hhyponitrtte,  NUrato-hypanUriie^ 
and  Ni^aUHnitrUe. 

Silver  NitraUHiitriie, — I  have  made  new  experiments  on  the  union 
of  silver  nitrate  with  silver  nitrite,  first  examined  by  me  in  1871 
(Trans.,  24,  85).  Silvel'  nitrite,  mixed  with  a  little  less  than  its 
equivalent  of  silver  nitrate,  suffers  only  slight  decomposition  until  it 


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PBEPABATION  BY  SODIUM  OR  POTASSIUM.  Ill 

melts  idong  with  the  nitrate  at  about  130^.  The  fused  salts  solidify 
at  about  125°  to  a  translucent,  greenish-yellow,  crystalline  nuu3S, 
except  in  the  uppermost  part,  where  it  is  opaque  from  the  presence  of 
bubbles  and  metallic  silver.  This  upper  part  removed,  the  rest  can 
be  fused  again  without  suffering  further  change,  and  even  be  heated 
nearly  to  180°  without  decomposing.  Silver  nitrite,  heated  alone, 
shows  marked  change  of  colour  when  the  temperature  has  reached 
120%  gives  red  fumes  at  about  140°,  and  very  freely  decomposes 
below  180°  without  showing  signs  of  fusing.  Silver  nitrate  does  not 
fuse  below  217°  (Carnelly).  The  low  melting  point  of  the  mixture  of 
the  two  salts,  and  the  increased  stability  of  the  nitrite,  are,  however, 
the  only  facte  showing  that  there  is  any  chemical  union,  for  water 
separates  the  two  salts. 

Ifon^asiatence  qf  NUnUa-hyponiPrite. — Silver  hyponitrite  (4  parts)  and 
silver  nitrate  (5  parts),  in  intimate  mixture,  wei'e  heated  in  a  bath. 
Ko  change  was  observed  until  175°  was  reached,  when  fusion  and  the 
evolution  of  red  fumes  occurred.  The  hyponitrite  had  then  disap- 
peared, and  the  fusion  may  be  attributed  to  the  decomposition  of  the 
hyponitrite,  as  usual,  into  nitric  oxide,  among  other  things,  and  to 
the  interaction  of  this  nitric  oxide  with  some  of  the  nitrate  to  form 
the  fusible  nitrato-nitrite. 

The  attempt  was  also  made  to  prepare  a  compound  of  the  two  salts 
in  presence  of  water,  there  being  some  grounds  to  expect  success. 
Galcium  hyponitrite,  a  nearly  insoluble  salt,  was  ground  up  with 
excess  of  a  very  concentrated  solution  of  silver  nitrate,  and  a  dense 
and  strongly  yellow  precipitate  obtained,  which  was  washed  with 
water  until  all  the  calcium  salt  had  been  removed ;  the  precipitate 
was  still  yielding  up  a  little  silver  nitrate  when  the  washing  was 
stopped.  Drained  on  a  tile  and  dried  in  a  vacuum,  it  proved  to  be 
somewhat  sensitive  to  light  and  to  heat,  but,  as  it.  contained  76*94 
per  cent,  of  silver,  and  could  have  been  washed  more  free  from  silver 
nitrate,  a  combination  of  the  two  salts  stable  in  water  does  not  exist. 
All  that  can  be  said  is  that  silver  hyponitrite  requires  long  washing 
to  remove  the  last  portions  of  silver  nitrate. 

NitriUhhyponitrUe  ako  nanrexiaterU. — In  a  paper  already  referred 
to,  I  have  recorded  obtaining  a  minute  quantity  of  what  appeared  to 
be  hyponitrite,  when  partially  decomposing  silver  nitrite  by  heat, 
that  is,  a  bright  yellow  substance  insoluble  in  water  and  soluble  in 
ammonia.  I  have  failed  to  get  this  again.  Silver  hyponitrite  and 
sOver  nitrite,  heated  together,  show  no  change  until  decomposition 
and  the  escape  of  red  fumes  occur,  and  then  all  hyponitrite  has  been 
destroyed. 

When  making  known  his  observation  of  the  interaction  of  hydroxyl- 
amine  and  nitrous  acid  in  1893,  Paal  stated  that,  from  a  solution  of 

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112   DIVERS:   HYPONITRITES ;  THEIR  PROPERTIES,   AND  THEIR 

alkali  byponitrite  which  also  contained  nitrite,  silver  nitrate  had  pre- 
cipitated a  substance  which,  althongb  it  was  like  silver  byponitrite, 
proved  to  be  a  silver  nitrito-byponitrite.  It  gave  no  silver  nitrite,  even 
to  hot  water,  and  could  be  dissolved  in  cold  dilute  nitric  acid,  and  be 
reprecipitated  with  ammonia  without  suffering  change  in  composition. 
It  was  less  stable  than  the  simple  byponitrite  when  heated,  gave  the 
reactions  of  a  nitrite  along  with  those  of  a  byponitrite,  and  yielded 
numbers  (not  quoted),  on  analysis  for  silver,  which  agreed  nearly 
with  that  required  by  the  formula  AgjN^Og.  Ten  years  previously, 
Berthelot  and  Ogier,  probably  under  similar  conditions,  got  similar  re- 
sults, except  that  they  were  led  by  their  analysis  to  give  the  formula 
Ag^N^Og  to  the  substance  they  had  obtained.  It  is  true  that,  in  spite 
of  endeavours  to  purify  it,  silver  byponitrite  retains  with  obstinacy 
enough  nitrite  to  give  the  iodide  and  starch  reaction  for  a  nitrite,  and 
that  it  often,  through  the  presence  of  impurities,  gives  low  results  for 
the  silver ;  but,  beyond  these  admissions,  I  cannot  subscribe  to  the 
accounts  given  by  the  chemists  just  named  as  to  the  existence  of  com- 
pounds of  silver  byponitrite  with  silver  nitrite. 

I  have  reduced  sodium  nitrite  by  sodium  amalgam  as  usual,  and 
dissolved  in  the  solution  one-sixth  as  much  more  sodium  nitrite  as  had 
been  reduced,  thus  getting  byponitrite  and  nitrite  together  in  solution 
in  about  equivalent  proportions,  in  accordance  with  the  experience 
recorded  in  this  paper.  The  precipitation  of  silver  byponitrite  was 
then  proceeded  with,  in  one  experiment,  without  previous  neutralisa- 
tion of  sodium  hydroxide,  and  in  another  experiment  after  neutralisa- 
tion of  the  alkali.  The  result  was  the  same  in  both  experiments. 
There  was  a  bright  yellow  precipitate,  not  noticeably  different  from 
ordinary  hyponitrite,  and  the  mother  liquor  retained  much  alkali 
nitrite  or  silver  nitrite  in  the  respective  cases ;  the  precipitate  was 
repeatedly  washed  with  cold  water,  but  the  washing  was  stopped  when 
very  little  silver  was  being  extracted.  It  proved  to  be  somewhat 
sensitive  to  light  and  heat.  It  was  dried  in  the  cold  and  in  a  vacuum, 
and  the  silver  was  then  determined  ;  this  was  769  per  cent.  Nitrite 
could  be  easily  detected  in  it,  but  the  compound  AgjNjO,  would  have 
only  74  per  cent,  of  silver,  and  Ag^^fi^  only  76  per  cent.  Besides 
this,  by  prolonged  washing  the  byponitrite  can  be  made  much  purer. 
These  experiments,  therefore,  afford  no  evidence  of  the  existence  of 
such  a  compound  as  Paal  has  described. 

Fropertiea  of  a  Solution  qf  Hyponitrous  Acid. 

Solutions  of  hyponitrous  acid  are  always  prepared  in  one  way, 
namely,  by  decomposing  silver  hyponitrite  with  just  sufficient  dilute 
hydrochloric  acid.     Hyponitrous  acid  has  been  obtained  by  Hantzsch 


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PREPARATION   BY   SODIUM  OR   POTASSIUM.  113 

and  Kaufmann  in  crTstals  very  deliquescent  and  very  unstable,  by 
using  dry  ether  in  place  of  water  in  its  preparation.  The  acid  in 
dilute  aolution  reddens  litmus  not  so  strongly  as  nitric  acid,  but  much 
more  than  carbonic  add.  On  drying  the  reddened  litmus  paper,  it 
becomes  blue  again.  A  solution  of  the  acid  becomes  neutral  to 
litmus  when  half  the  quantity  of  baryta  water  or  alkali  required  to 
form  the  normal  salt  has  been  added  (Zorn),  and  such  a  solution,  by  de- 
composition, soon  acquires  the  4)roperty  of  blueing  red  litmus  paper. 
When  neutral  to  litmus,  the  solution  is  also  neutral  to  phenol- 
phthalein  (Thum).  When  neutralised  with  baryta,  and  very  rapidly 
evaporated  under  reduced  pressure,  hyponitrous  acid  yields  an  acid 
salt  which  is  crystalline  and  extremely  unstable  (Zorn). 

It  decomposes  silver  carbonate,  if  not  also  lead  and  other  car- 
bonates ;  it  also  decomposes  silver  nitrate  and  sulphate.  It  does  not 
oxidise  hydrogen  iodide  (iodide  and  starch  reagent),  and  is  not 
oxidised  by  iodine  solution  or  by  the  air.  It  is  oxidised  by  nitrous 
add  and  the  stronger  oxidising  agents.  No  way  of  deoxidising  or 
hydrogenising  hyponitrous  acid  is  known ;  it  entirely  resists  the 
action  of  sodium  amalgam,  and  also,  according  to  Thum,  that  of 
zinc  and  sulphuric  acid.  Ethylic  hypomtrite  is  reduced,  apparently,  by 
tin  and  acetic  or  hydrochloric  acid  to  alcohol  and  nitrogen,  according 
to  Zorn,  but  as,  also  according  to  him,  it  slowly  decomposes  by  itself, 
when  moist,  into  nitrogen,  alcohol,  and  aldehyde,  there  is  sufficient 
reason  to  doubt  that  this  reduction  by  tin  and  acid  is  anything  more 
than  the  hydrogenisation  of  the  aldehyde. 

Hyponitrous  acid  slowly  decomposes  into  nitrous  oxide  and  water. 
A  strong  solution  soon  effervesces,  gently  in  the  cold,  freely  when 
heated,  just  like  a  solution  of  carbon  dioxide,  and  some  hyponitrites 
in  presence  of  only  a  little  water  effervesce  with  an  acid.  A  solu- 
tion of  one  or  two  grams  of  the  acid  in  a  litre  of  water  kept  in  ice 
hardly  falls  noticeably  in  strength  in  one  hour^  but  at  25 — 30°  it 
may  lose  a  sixth  of  the  acid  by  decomposition  in  24  hours ;  at  a 
lower  temperature,  Thum  observed  a  loss  only  half  as  great  in  the 
same  time.  Alkali  hyponitrites  in  solution  also  decompose  into 
nitrous  oxide  and  alkali,  gradually  in  the  cold  and  rapidly  when 
heated ;  alkali  hydroxides  impede  the  decomposition,  and  when  highly 
concentrated  stop  it  altogether,  apparently  (see  p.  98) ;  neutralisa- 
tion of  the  alkali  even  by  carbonic  acid  hastens  the  decomposition, 
as  a  matter  of  course,  but  there  is  no  evidence  that  carbonic  acid  is 
able  to  decompose  a  hyponitrite,  as  it  has  been  said  to  do. 

Hyponitrous  acid  solution  dissolves  silver  hyponitrite  slightly. 
The  alkali  salts  of  hyponitrous  acid  dissolve  silver  hyponitrite  some- 
what more  freely,  and  also  decompose  silver  chloride  (see  p.  102) ; 

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114  DIVERS:  HYPONITRITES  ;  THEIR  PROPERTIES,  AND  THEIR 

they  give  precipitates  with  barium   and   calcium   salts,  and   with 
solutions  of  most  metallic  salts. 

Other  substances  are  liable  to  be  present  in  the  solution  of  hypo- 
nitrous  acid,  and  this  fact  has  certainly  caused  the  properties  of  the 
acid  to  be  wrongly  described  in  some  respects.     In  one  point,  this  is 
the  case  in  my  first  paper,  in  which,  however,  there  was  a  warning 
that  the  crude  solution  of  the  acid,  which  had  been  examined,  might 
have  reacted  as  it  did  partly  through  the  presence  of  other  unrecog- 
nised substances  in  it.      That  solution    decolorised  iodine  water, 
and  prevented  the  action  of  nitrous  acid  on  an  iodide  ;  this,  however, 
was  not  due  to  the  hyponitrous  acid,  but  to  a  very  little  hydroxyl- 
amine,  the  presence  of  which  was  unrecognised.     Kirschner  has  again 
given  to  hyponitrous  acid  the  property  of  decolorising  iodine  water 
to  a  slight  extent.     In  his  case,  the  substance  acting  on  the  iodine 
must  have  been  a  trace  of  sulphur  dioxide,  for  he  made  his  solution 
of  the  acid  from  silver  hyponitrite  that  had  been  prepared  by  the 
hydroxyamidosulphonate  method.     I  can  confirm  the  accuracy  of  his 
observation.     Even  when  the  silver  hyponitrite  has  been  most  care- 
fully precipitated  so  as  to  avoid  all  sensible  precipitation  of  sulphite, 
and  has  been  dissolved  in  dilute  acid  and  reprecipitated,  it  still 
gives  a  solution  of  hyponitrous  acid  capable  of  acting  on  a  very  little 
iodine  water ;  but  then  no  more  iodine  was  taken  up  although  there 
was  hyponitrous   acid   in   the   solution.      On   the   other   hand,  the 
acid  prepared  from  silver  hyponitrite  not  derived  from  hydroxyamido- 
sulphonate does  not  decolorise  iodine  at  all,  as  Thum  first  pointed  out. 
Hyponitrous  acid,  according  to  van  der  Plaats,    liberates  iodine 
from  potassium  iodide ;  according  to  Thum  and  my  first  paper,  it  does 
not,  whilst  according  to  Hantzsch  and  Kaufmann  it  is  only  just  at 
first  that  it  does  not  do  so.     The  last-named  chemists,  therefore,  state 
that  the  acid  does  not  itself  liberate  iodine,  but  quickly  begins  to 
yield  nitrous  acid  which  does  liberate  it.     They  also  found  hypo- 
nitrous acid  to  yield  ammonia,  but  iivalater  publication  Hantzsch  and 
Sauer  state  that  the  ammonia  was  an  impurity  in  the  silver  hypo- 
nitrite from  which  the  acid  had  been   prepared.      Even  with  the 
simultaneous  formation  of  the  ammonia,  it  is  difficult  to  understand 
the  generation  of  nitrous  acid.     These  authors,  invoking  the  aid  of 
tautomerism,  suppose  that  the  hydrogen  leaves  oxygen  for  nitrogen, 
giving  the  unknown  substance  HNIO,  which  then  beoomes  NH3  -f 
N2O3,  and  these  again  pass  into  HNOg  +  N^  +  OHj.     In  place  of  this 
series  of  improbable — I  would  say,  unnatural — changes,  I  suggest 
that,  if  indeed  such  change  occurs  at  all,  it  must  be  into  water,  nitric 
oxide,  and  nitrogen,  the  nitric  oxide  then  oxidising  to  nitrous  acid. 
But  I  am  strongly  disposed  to  deny  that  hyponitrous  acid  decomposes 


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PREPARATION  BY  SODIUM  OR  POTASSIUM.  115 

of  itself  into  anything  but  what  are  certainly  its  main  products, 
nitrous  oxide  and  water.  My  reasons  are  several.  First,  there  is  the 
unlikelihood  that  the  diazo-radidei  NIN,  should  resolve  itself  into 
mono-nitrogen  compounds,  such  as  NO,NH,,NO*OH  or  {VO)fif  in- 
stead of  Q^^yy,  Secondly,  there  is  the  fact  that  time  comes  in  as  the 
condition  of  the  production  of  nitrous  acid,  and  that  a  rise  in  tem- 
perature does  not.  A  solution  of  hyponitrous  acid  of  fair  purity, 
if  boiled  or  quickly  evaporated  gives  nothing  but  nitrous  oidde  and 
water ;  and  only  very  slowly  and  to  a  very  small  extent  does  nitrous 
acid  appear  in  a  cold  solution  of  the  purest  acid.  Thirdly,  the  greater 
the  care  taken  to  reduce  and  exclude  all  nitrite  in  preparing  the 
hyponitrous  add  solution,  the  longer  will  be  the  time  before  any 
sensible  quantity  of  nitrous  acid  develops,  and  the  more  gradually 
will  the  quantity  increase.  From  these  facts,  the  almost  necessary 
inference  is  that  the  whole  of  the  nitrite  has  never  been  entirely 
removed  or  excluded  in  preparing  the  acid,  and  that  what  has  been 
left,  although  too  minute  in  quantity  to  afEect  the  iodide  test  (which 
requires  1  in  20  millions,  according  to  Warington),  yet  multiplies 
itself  by  interaction  with  the  hyponitrous  acid,  forming  nitric  oxide, 
which  is  further  oxidised  to  nitrous  acid  by  the  air  dissolved  in  the 
solution  (HNO)j  +  2HNO,  =  2H20  +  4NO-*4HN02.  This  aerial  oxi- 
dation can  be  demonstrated  in  such  a  solution  of  hyponitrous  acid  as 
that  which  Hantzsch  and  Kaufmann  employed  in  their  experiments, 
which  gave  the  blue  of  the  iodide  test  almost  immediately ;  it  is  only 
necessary  to  leave  one  portion  of  the  solution  in  a  deep,  narrow  vessel, 
such  as  a  test  tube  half  full,  and  another  portion  in  a  shallow  basin  for 
10  minutes,  and  then  apply  the  test,  when  the  solution  in  the  basin  will 
be  found  to  liberate  more  iodine  than  that  in  the  tube.  If,  in  reducing 
the  sodium  nitrite,  its  concentrated  solution  is  shaken  with  excess  of 
the  amalgam  for  an  hour  or  two  after  its  main  reduction,  and  the 
solution  is  then  either  diluted,  acidified  cautiously  with  dilute  sul- 
phuric add,  and  tested,  or  is  predpitated  by  silver  sulphate,  away 
from  the  light  as  far  as  practicable,  and  the  predpitate  washed  in  the 
dark  and  converted  into  the  add  and  tested,  either  solution,  when 
mixed  with  the  iodide  reagent,  will  not  blue  in  the  least  for  an  hour 
or  more  in  the  dark,  and  provided  the  constituents  of  the  reagent  are 
pure  enough  and  properly  used.* 

Against  the  view,  which  may  be  advanced,  that  hyponitrous  acid 
becomes  nitrous  add  through  oxidation  by  the  air,  I  must  point  out 

*  My  way  of  applying  the  test  is  that  followed  by  Warington  (Ohenu  Nitws, 
1885,  61,  89),  except  that,  having  potassimn  iodide  of  high  quality,  I  need  it 
instead  of  l^mmsdorfs  zino  iodide  solution.  In  the  dark,  a  blank  test  will  remain 
for  houB  without  the  least  blueing.  There  is  no  advantage  in  uiing  acetic  acid 
in  plaee  of  pnn  sulphurio  or  hydrochloric  add. 

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116  DIV£BS:   HTPONITBITSS ;  THEIB  PROPERTIES,  AND  THEIR 

that  it  is  difficult  to  admit  that  if  the  nitrous  acid  has  such  origiui  it 
should  form  so  very  slowly.  A  way  occurred  to  me  which  must  be  used 
for  deciding  this  point,  so  far  as  the  exclusion  of  nitrous  acid  goes,  but 
it  has,  in  my  opinion,  not  served  to  do  so.  If,  in  preparing  sodium 
ozimidosulphonate,  the  sulphur  dioxide  is  used  in  excess,  every  trace 
of  nitrite  ought,  presumably,  to  be  sulphonated ;  if,  then,  the  oximido- 
sulphonate  is  fuUy  hydrolysed  into  hydroxyamidosulphonate,  as  it 
presumably  can  be,  then,  when  the  latter  is  converted  into  hyponitrite 
and  sulphite  by  potassium  hydroxide,  there  will  be  no  oximido- 
sulphonate  present  to  simultaneously  revert  to  nitrite  and  sulphite. 
Therefore,  the  silver  hyponitrite  from  such  a  source  should  be  obtain- 
able absolutely  free  from  nitrite,  and  should  furnish  a  solution  of 
hyponitrous  acid  also  free  from  nitrous  acid.  Such  silver  hyponitrite 
I  endeavoured  to  prepare,  and  then  tested  the  acid  got  from  it.  The 
issue  was,  however,  complicated  by  the  fact  that  such  an  acid  is  not 
quite  free  from  sulphurous  acid,  as  was  shown  by  its  decolorising  a 
minute  quantity  of  iodine  solution.  That  it  also  did  not  act  for  a  time 
on  the  iodide  and  starch  reagent  was  due  in  part  to  this  cause.  The 
solution  did,  however,  give  a  blue  coloration  with  the  reagent  sooner 
than  a  corresponding  blank  test.  But  this  was  no  proof  that  hypo- 
nitrous  acid  passes  spontaneously  into  nitrous  acid,  for,  first,  there  is 
the  possibility  of  nitrous  acid  having  been  present  through  incomplete 
sulphonation  and  hydrolysis  in  preparing  the  hyponitrite ;  this  nitrous 
acid  would,  indeed,  have  been  converted  into  nitric  oxide  by  the 
sulphurous  acid  retained  by  the  silver  salt,  but  when  all  this  was 
gone,  the  nitric  oxide  would  have  become  nitrous  acid  again  by 
oxidation.  Secondly,  it  is  almost  certain  that  the  oxidation  of  the 
sulphurous  acid  by  the  air  would  have  induced  oxidation  of  some  hypo- 
nitrous  acid,  in  accordance  with  the  observations  of  Mohr,  M.  Traube, 
van't  HofE  and  Jorissen,  Engler  and  Wild,  Bach,  ^. 

QuaTUitative  Estimation  qf  ffj^ponitrous  Add. — Hyponitrous  add  can 
be  estimated  accurately,  both  gravimetrically  (Zom)  and  volumetrically 
(Thum).  Solutions  of  the  free  acid,  or  of  its  alkali  salts  in  water,  or 
of  its  other  salts  in  very  dilute  and  cold  nitric  acid  are  mixed  with 
excess  of  silver  nitrate,  and  then  the  free  acid  is  just  neutralised  with 
sodium  carbonate  or  with  ammonia.  The  washed  precipitate  is  either 
dried  and  weighed  as  such,  or  weighed  as  metal  or  as  chloride. 

Yolumetrically,  the  acid  can  be  estimated  in  solution  in  the  free 
state  and  unmixed  with  any  other  acid,  by  adding  excess  of  solution 
of  potassium  permanganate,  leaving  it  for  a  quarter  of  an  hour,  then 
adding  sulphuric  acid,  allowing  it  to  remain  for  another  quarter  of  an 
hour,  warming  to  30^,  adding  a  known  quantity  of  oxalic  acid  sufficient 
to  decolorise,  and,  finally,  titrating  back  with  permanganate.  The 
hyponitrous  acid  is  thus  oxidised  to  nitric  acid.    The  oxalic  acid  should 


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PBEPARATION  BT  SODIUM  OR  POTASSIUM.  117 

be  decinormal,  and  the  solution  of  permanganate  be  volumetrically 
equivalent  to  it.  Ferrous  sulphate  is  unsuitable  for  use  in  place  of 
oza&ic  acid.  The  process  is  an  excellent  one.  Hantzsch  and  Sauer 
failed  to  get  good  results,  because  they  deviated  from  Thum's  diiec- 
tiona  by  acidifying  the  permanganate  before  adding  it  to  the  hypo- 
nitrite.  Elirschner  also  was  unsuccessful  with  this  process,  but  his 
failure  is  also  explained  by  his  deviation  from  Thum's  directions.  He 
added  nearly  insoluble  salts,  such  as  the  barium,  strontium,  or  silver 
hyponitrite,  to  the  potassium  permanganate,  so  that  the  base  of  the 
salt  was  present,  and  the  hyponitrous  acid  locally  in  excess  of  the  per- 
manganate ;  he  then  added  the  sulphuric  acid,  apparently  immediately! 
and  used  ferrous  snlphate  for  titrating  back. 

Taking  5  c.c.  of  normal  hydrochloric  acid,  largely  diluting  it,  adding 
ice  and  a  cream  of  precipitated  silver  hyponitrite  so  as  to  exactly  use 
up  all  the  hydrochloric  acid,  making  up  to  100  c.c,  and 'decanting 
from  the  bulk  of  the  silver  chloride,  I  obtained  a  solution  which, 
although  somewhat  turbid  from  silver  chloride,  gave,  in  successive 
portions  of  20  cc,  all  tested  within  an  hour,  quantitative  results 
corresponding  well  with  0*155  gram  hyponitrous  acid  in  100  c.c,  that 
isy  the  quantity  equivalent  to  the  hydrochloric  acid  taken  ;  next  day, 
the  remainder  of  the  solution  (in  very  hot  weather)  showed  the  presence 
of  0-131  gram  of  the  add  in  100  cc. 

Thum  found  that,  in  alkaline  solution,  alkali  hyponitrite  is  quanti- 
tatively converted  into  nitrite  by  permanganate.  Although  I  have 
not  examined  this  point  myself,  I  find  that  nitrite  is  thus  formed, 
and  that  nitric  acid  is  formed  in  Thum's  acid  permanganate  method. 
Kirsehner  doubts  that  either  is  produced. 


Barium,  Stnmtiwn^  and  Calcium  HyponUritea. 

Barium  hypofUkite  has  been  obtained  by  Zorn,  Maquenne,  and 
Kirsehner,  and  is  most  simply  prepared  by  adding  barium  chloride  to 
a  concentrated  solution  of  sodium  hyponitrite  and  stirring  well.  It 
is  crystalline,  almost  insoluble,  and  an  unstable  and  exceedingly 
efflorescent  salt,  but  Kirsehner  has  succeeded  in  determining  its  water 
of  eiystaUisation  satisfactorily.  Its  formula  is  BaNgOj  +  iHjO.  A 
crystalline  acid  salt  exists  (Zorn). 

Straniiufn  hyponitrite^  SrNjOj  +  SH^O,  Maquenne,  Elirschner. 

Caleivm  hyponitrite,  CaNjOj  +  iH^O,  Maquenne,  Kirsehner.*  This 
is  crystalline,  very  sparingly  soluble,  stable,  not  losing  its  water  even 
over  sulphuric  acid.  I  find  that  it  can  be  easily  precipitated  from  a 
fairly  concentrated  solution  of  sodium  hyponitrite,  and  can  thus  be 
prepared  more  easily  than  in  the  ways  followed  by  Maquenne  and  by 

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118  DIVERS:  HYPONITRITBS ;  THEIR  PROPERTIES,   AND  THEIR 

Eirschner,  using  the  silver  salt.  On  account  of  its  stabilityi  it  is  a 
good  hjponitrite  to  keep  in  stock.  It  is  sufficiently  soluble  for  its 
solution  to  serve  to  show  the  reactions  of  a  hyponitrite  with  silver, 
mercuric,  mercurous,  copper,  lead,  and  other  salts. 


Calcium,  Strontium,  and  Barium  HyponUrosoacetaUi. 

Some  remarkable  salts  have  been  described  by  Maquenne,  having  the 
composition  expressed  by  the  f  ormulsa 

BaN,O^Ba(C,H302)2,(C,H,0,)2+  3H,0. 
T  have  prepared  and  partly  analysed  the  calcium  salt,  following 
Maquenne's  process,  which  is  to  dissolve  calcium  hyponitrite  in  30  per 
cent,  acetic  acid  until  the  new  salt  begins  to  crystallise  out.    I  kept 
the  acid  at  about  50°  while  dissolving  in  it  nearly  as  much  of  the 
calcium  salt  as  it  would  take  up,  the  salt  being  deposited  on  cooling. 
It  is  remarkable  that  this  can  be  done  without  causing  more  than  very 
slight  effervescence.     The  salt  crystallises  in  short  prisms,  stable  for 
many  days,  very  soluble  in  water,  in  which  it  gives,  with  silver  nitrate, 
the  yellow  hyponitrite.     In  spite  of  its  acid  composition,  it  is  neutral 
or  even  slightly  alkaline  to  litmus.    To  account  for  its  existence  and 
neutral  reaction,  I  suggest  for  it  the  constitution  expressed  by  the 
formula 

Ca{OAc)j.Ca<g^^«'  ^^°  +  5H,0. 

This  represents  it  as  being  normal  calcium  acetate  with  one-fourth  oi 
its  oxylic  oxygen  replaced  by  the  hyponitrite  radicle,  or  as  a  doubl 
anhydride  of  calcium  acetate  and  hyponitrite.  It  is  thus  made-  out  t 
have  a  constitution  analogous  to  that  of  a  (hypo)nitroso8ulpbate,  a 
determined  by  Haga  and  me  (Trans.,  1895,  67,  1098), 

Simple  hyponitrosoacetic  acid,  C^HgO'O 'N^*  OH,  would  be  isomei 
with  acetonitrosohydroxamic  acid,'^C2H30-N(NO)*OH,  which  Santzs 
and  Sauer  have  been  trying  to  prepare.  The  hyponitrosoaoetal 
are  much  more  stable  in  water  than  the  (hypo)nitrososulpliate8, 
difference  perhaps  connected  with  the  fact  that  sulphuric  acid  ioni 
largely,  while  both  acetic  acid  and  hyponitrous  acid  ionise  very  litl 
Heated  with  water,  the  hyponitrosoacetates  decompose  like  tlie  (by] 
nitrososulphates  do  in  cold  water. 


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PREPARATION  BY  SODIUM  OR  POTASSIUM.  119 


Mercuric  Hypanitrite, 

Mercuric  hyponitrite  is  a  particularly  interesting  salt  and  has^not 
as  yet  been  described.  R&y  has,  indeed,  described  some  compounds 
vbicb  be  regards  as  being  basic  mercuric  hyponitrites,  but  obtained 
under  conditions  suggesting  the  probability  that  they  are  something 
quite  different ;  moreover,  he  has  not  as  yet  proved  them  to  be  com- 
pounds of  this  class.  One  of  them  he  obtained  by  the  interaction  of 
solutions  of  mercuric  nitrite  and  potassium  cyanide,  a  very  interesting 
and  remarkable  result,  should  it  be  confirmed.  In  any  case,  his  pre- 
cipitates appear  to  have  nothing  at  all  in  common  with  the  normal 
salt  here  described,  and  cannot  be  obtained  in  thd  ordinary  way.  The 
existence  of  this  salt  was  indicated  by  me  in  1871. 

Mercuric  hjrponiirite  is  obtained  from  sodium  hyponitrite  and 
mercuric  nitrate  by  precipitation ;  the  solution  of  sodium  hyponitrite 
and  hydroxide,  obtained  by  reducing  sodium  nitrite,  is  largely  diluted 
and,  while  ice  cold,  nearly  or  quite  neutralised  with  dilute  nitric  acid  ; 
it  is  then  (mercurous  nitrate  serving  as  indicator,  see  p.  97)  poured 
into  a  mercuric  nitrate  solution,  which  must  not  be  in  excess  and 
should  contain  as  little  free  acid  as  possible.  The  slightly  turbid 
mother  liquor  is  quickly  decanted  from  the  precipitate  formed,  and 
after  being  neutralised  with  sodium  carbonate  is  mixed  with  more 
mercuric  nitrate,  the  whole  poured  back  on  to  the  main  precipitate, 
stirred  up  with  it,  and  soon  again  decanted.  The  precipitate  should 
be  washed  quickly  by  decantation,  since  it  is  liable  to  be  quickly 
destroyed  by  the  slightly  acid  mother  liquor. 

It  is  a  flooculent,  cream-coloured  precipitate,  easily  washed  on  the 
filter,  and  dries  up  to  a  light  buff-coloured  powder,  this  colour  being 
due,  probably,  to  incipient  change  into  the  mercurous  salt.  Dried 
quickly  in  the  air,  on  a  porous  tile,  it  is  hydrated,  having  the  formula 
{Qjg^fi^^'\-Z'S.fiy  but  if  dried  in  the  desiccator  it  is  anhydrous. 
Being  a  little  sensitive  to  light,  it  should  be  dried  in  the  dark.  It 
dissolves  in  hydrochloric  acid  and  in  sodium  chloride  solution,  but  it  is 
unstable,  changing  into  the  mercurous  salt,  and,  therefore,  is  liable  to 
show  turbidity  in  the  chloride  solutions.  The  mercury,  precipitated  as 
sulphide  from  a  solution  of  the  anhydrous  salt  in  hydrochloric  acid, 
was  found  to  be  76*71  per  cent.,  the  formula  HgNgOj  requiring  76*92 
per  cent.  Its  solubility  in  excess  of  sodium  chloride  does  not  prevent 
mercuric  chloride  giving  a  precipitate  with  sodium  hyponitrite.  The 
solubility  of  the  salt  in  sodium  chloride  is  a  qualitative  proof  of  its 
normal  composition.  The  alkalinity  of  the  solution  is  caused  by  the 
sodium  hyponitrite  generated  in  it.  Potassium  hydroxide  at  once 
decomposes  mercuric  hyponitrite  into  oxide,  without  showing  any 

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120  DIVERS:  HYPONITRITES  ;  THEIR  PROPERTIES,  AND  THEIR 

tendency  to  produce  basic  salts.     In  very  dilute  alkali,  the  precipitate 
is  slightly  soluble. 

What  makes  this  salt  so  remarkable,  not  only  as  a  hyponitrite,  but 
as  a  mercuric  salt,  is  the  nature  of  the  decomposition  which  it  under- 
goes. Slowly  or  quickly,  it  decomposes  into  mercurous  hyponitrite 
and  nitric  oxide — some  of  the  latter,  oxidised  by  the  air,  converting 
some  hyponitrite  into  nitrate.  No  other  mercuric  salt  decomposes 
into  mercurous  salt,  although  many  cupric  salts  change  into  cuprous 
salts.  Ferric  oxalate  shows  just  the  same  kind  of  change,  namely, 
into  ferrous  oxalate  and  carbon  dioxide.  The  most  closely  related 
change,  however,  is  that  of  sodium  (hypo)nitrososulphate  into  sulphite 
and  nitric  oxide,  the  very  phenomena  being  similar,  so  that,  except  for 
the  colour  change,  I  might  describe  my  experience  with  this  salt  in  the 
words  of  the  paper  by  Haga  and  me  on  sodium  (hypo)nitrososulphate 
(Trans.  1895,  67,  1095).  Thus,  having  on  one  occasion  left  some 
grams  of  salt  all  night  in  the  desiccator  in  the  form  of  a  pressed  cake, 
just  as  removed  from  the  filter,  I  noticed,  when  weighing  it  between 
watch-glasses,  that  it  was  losing  weight  on  the  balance-pan.  When  the 
glasses  were  opened,  a  strong  nitrous  odour  was  observed,  the  cake  soon 
became  grey,  white  on  the  surface,  and,  being  left  loosely  covered,  grew 
very  hot  and  gave  out  torrents  of  nitric  oxide ;  it  then  cooled,  and 
underwent  no  further  change,  even  in  the  course  of  months.  The 
whitish  colour  of  the  cake  was  found  not  to  penetrate  beyond  a  milli- 
metre into  it,  the  inside  being  of  a  uniform  yolk-yellow,  and  consisting 
of  mercurous  hyponitrite.  The  surface-coating  proved  to  be  mercurous 
nitrate,  largely  soluble  in  water,  and  had  evidently  been  produced 
with  the  assistance  of  the  oxygen  of  the  air.  Not  always,  however, 
does  the  change  occur  in  this  striking  and  rapid  way,  its  progress 
being  gradual  and  almost  imperceptible  until  complete. 

Mercuric  hyponitrite  is  decomposed  by  heat  largely  into  mercuric 
oxide  and  nitrous  oxide,  but  partly  into  metal  and  nitric  oxide. 


Other  Hyponitriiea, 

Mercwroua  Hyponitrite, — This  salt  has  been  prepared  and  analysed 
by  Thum  (Inaug,  Bits.,  Prag.  1893),  who  used  sodium  hyponitrite  and 
mercurous  nitrate  in  obtaining  it.  The  possibility  of  getting  it  by  the 
spontaneous  decomposition  of  mercuric  hyponitrite  has  just  been 
described.  RAj  has  also  evidently  obtained  it  in  a  very  impure  state, 
not  further  examined.  It  can  be  prepared  in  the  same  way  as 
mercuric  hyponitrite,  using  mercurous  nitrate  in  place  of  mercuric 
nitrate.  It  is  of  a  full  yellow  colour,  is  blackened  by  even  the 
weakest  solution  of  alkali,  and  is  soluble  in  dilute  nitric  acid,  from 


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PREPA.RATION   BY  SODIUM   OR  POTASSIUM.  121 

which  it  can  be  precipitated  by  sodium  carbonate.  It  is  a  stable  salt, 
but  is  blackened  by  bright  light.  Its  decomposition  by  heat  resembles 
that  of  the  mercuric  salt,  except  that  much  more  metal  is  produced, 
as  is  natural     Composition,  (ngON)2. 

Cupric  Hydroxide  Eyponitrite. — ^This  salt  was  described  by  me  in 
1871,  and  was  also  obtained  by  Kolotow  in  1890,  but  was  first  fully 
examined  by  Thum,  and  has  again  been  examined  by  Kirschner; 
being  a  basic  salt,  its  precipitation  from  normal  sodium  hyponitrite 
leayes  an  acid  mother  liquor,  on  neutralising  which  much  more  of  the  ' 
salt  precipitates.  It  is  of  a  bright  pea-green  colour,  and  very  stable. 
It  may  be  boiled  with  water  without  losing  its  colour,  but  is  decom- 
posed by  sodium  hydroxide  and  is  soluble  in  dilute  acids  and  ammonia. 
Thum  has  shown  its  composition  to  be  Cu(OH)NO.  It  gives  water, 
cupric  and  cuprous  oxides,  and  nitrous  and  nitric  oxides  when  heated. 
By  adding  copper  sulphate  in  excess  to  hydroxylamine  sulphate  and 
then  a  very  little  ammonia,  it  can  also  be  precipitated  in  small 
quantity. 

Cuprous  hyponiirUe  cannot  be  formed.  I  have  tried  to  get  it  by 
precipitating  sodium  hyponitrite  by  copper  sulphate  in  presence  of 
free  hydroxylamine,  but,  first,  cuprous  oxide  precipitated  and  then, 
by  atrial  oxidation,  the  basic  cupric  hyponitrite,  which  in  composition 
is  equivalent  to  that  of  cuprous  hyponitrite  combined  with  faiydroxyl 
(see  above). 

Lead  ffyponiiriie. — ^This  salt  was  also  briefly  described  by  me  and 
has  been  prepared  and  analysed  by  Thum ;  Kirschner  has  again  pre- 
pared and  analysed  it,  but  not  in  a  pure  state.  The  precipitate  is 
cream-yellow  and  flocculent,  but  soon  becomes  very  dense  and  sulphur- 
yellow  ;  its  first  state  is  probably  that  of  a  hydrate ;  Kirschner  has 
mistaken  it  for  a  basic  salt.  The  yellow  salt  is  PbNgO,.  As  Thum 
has  pointed  out,  the  yellow  precipitate,  when  formed  in  a  weak  acid 
solution,  is  crystalline  and  just  like  ammonium  phosphomolybdate.  It 
is  soluble  in  dilute  nitric  acid,  and  is  decomposed  by  sodium  hydroxide, 
but  not  by  sodium  carbonate  in  the  cold. 

Ammonium  Hydrogen  Hyponitrite. — ^This  salt  has  been  described  by 
Hantzsch  and  Kaufmann,  who  found  it  to  be  exceedingly  unstable,  as 
was  to  be  expected.  That  the  normal  salt  could  not  exist  had  already 
been  pointed  out  by  me,  and  by  Zorn  ;  D.  H.  Jackson  believes,  how- 
ever, that  he  did  obtain  it  in  small  quantity  in  prismatic  crystals,  but 
this  is  exceedingly  improbable. 

Ethylic  Hyponitrite. — ^This  alkylic  salt  was  prepared  by  Zorn,  and  its 
vapour-density  taken  by  him.  It  is  very  explosive,  and  is  not  saponi- 
fied by  potassium  hydroxide.  In  the  moist  state,  it  slowly  decomposes 
into  nitrogen,  alcohol,  and  aldehyde. 

Benzylie   Hyponitrite. — Hantzsch    and    Kaufmann  have   prepared 

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122  DIVERS:  HTPONITRITES ;   THEIR  PROPERTIES,  AND  THSIB 

benzylic  hyponitrite  and  determined  its  molecular  magnitude  cryoscopi- 
cally.     It  undergoes  similar  decomposition  to  the  ethylic  salt. 

Constitution  of  the  ffypomiritea. 

MoleciUar  Magnitude, — In  my  first  paper,  nothing  could  be  said  as  to 
the  molecular  magnitude  and  constitution  of  the  hyponitrites.  In  1878, 
Zorn  fully  determined  their  molecular  magnitude,  finding  it  to  be  that 
containing  1^^*  ^^^^y  by  establishing  the  existence  of  an  aoid  barium 
salt  and  illustrating  the  similarity  of  hyponitrites  to  carbonates 
(a  point  which  had  already  been  noticed  by  me),  and  then 
by  preparing  ethylic  hyponitrite  and  taking  its  vapour-density  at 
reduced  pressure  (Hofmann^s  method).  It  would,  therefore,  be  unjust  to 
the  memory  of  this  x^hemist  to  admit  Hantzsch's  claim  {Annalen,  1898, 
299,  68)  to  have  finally  established  this  point  by  determining  cryoscopi- 
cally,  in  conjunction  with  Kaufmann,  the  molecular  magnitude  of 
hyponitrous  acid  in  water  and  of  benzylic  hyponitrite  in  acetic  acid, 
valuable  as  these  determinations  are.  The  possibility  of  determining 
the  molecule  of  the  acid  in  its  solution  in  water  rests  upon  the  fact, 
also  ascertained  by  these  chemists,  that  the  acid  only  slightly  ionises 
even  in  very  dilute  solution.  Maquenne,  by  a  somewhat  uncertain 
form  of  the  cryoscopic  method,  has  also  shown  that,  in  calcium  hypo- 
nitrosoacetate,  the  hyponitrite  radicle  cannot  be  less  than  N^Oj.  The 
strong  alkalinity  of  the  alkali  salts,  and  the  want  of  action  on  litmus 
of  their  partially-neutralised  solution,  first  pointed  out  by  me,  and 
the  solubility,  although  only  slight,  of  silver  hyponitrite  in  hypo- 
nitrous  acid  solution  (Thum)  and  in  alkali  hyponitrite  solution,  are 
also  facts  in  accordance  with  the  dihydric  composition  of  the  acid. 
Other  chemical  evidence  of  the  diazo-grouping  in  hyponitrites  is 
afforded  by  the  fact  of  the  difficulty,  if  not  impossibility,  of  deoxidising 
or  hydrogenising  them  (seep.  113).  The  derivation  of  hyponitrites 
from  the  interaction  of  hydroxylamine  and  nitrous  acid  would  only 
afford  evidence  of  the  diazo-magnitude  of  the  molecule,  if  the  hypo- 
nitrite produced  were  much  larger  in  quantity  than  what  can  be 
obtained  from  hydroxylamine  by  other  oxidising  agents,  or  from  nitrous 
acid  by  other  reducing  agents. 

My  colleague.  Assistant  Professor  Ikeda,  has  kindly  made  some 
determinations  of  the  molecular  magnitude  of  sodium  hyponitrite  by 
Loewenherz's  method  (Zeit.  physikeU,  Chem,  1896, 18,  70),  in  which  the 
lowering  of  the  freezing  point  of  melted  hydrated  sodium  sulphate  by 
another  sodium  salt  is  observed  ;  Loewenherz  found  that  sodium  salts 
behave  towards  the  water  of  hydrated  sodium  sulphate  almost  as  non- 
electrolytes.  Prof.  Ikeda,  in  his  experiments,  employed  sodium 
thiosulphate  in  place  of  sulphate,  but  only  because  he  had  been  working 


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PREPARATION  BT  SODIUM  OR  POTASSIUM.  123 

with  that  salty  and  had  had  large  experience  with  it.  Unfortunately, 
the  anhydrous  sodium  hyponitrite  I  could  furnish  at  the  time  was 
contaminated  with  4  or  5  per  cent,  of  carbonate  (same  mol.  wt.),  so 
that  the  determination  of  the  molecular  magnitude  can  only  be  regarded 
as  approximate.  But  it  is  amply  sufficient  to  decide  between  NaON  = 
53y  and  (NaON),^  106,  if  that  were  any  longer  necessary,  after  Zorn's 
decisive  researches,  supplemented  by  those  of  Hantzsch  and  Kauf  mann. 
Prof.  Ikeda  has  given  me  the  following  details. 

M.  p.  of  NajSj03  +  5H30  =  48-4°  (Tilden  found  48-6'^) ; 

H.  of  fusion  =  42-8  Cal.  (Ikeda)  ; 

Wt.  of  thiosulphate  used  »  40*9  grams ; 

Wt.  of  sodium  hyponitrite  used»^  grams ; 

Dp.  of  solidifying  pt.  =  AT° ; 

MoL  wt.  of  hyponitrite  »  m. 


1 

9 
40-9 

2(273 +  48-4)« 
42-8 

-&"»••■ 

9- 

aT°. 

m. 

0-162 

0116 

166 

0-467 

0-509 

108 

1066 

1-260 

100 

1-238 

1-607 

97 

In  cases  where  no  decomposition  of  the  salt  occurs,  the  method  gives 
results  too  high,  as,  for  example,  78*6  instead  of  69,  for  sodium 
nitrite ;  but  taking  into  consideration  the  partial  hydrolysis  of  the 
hyponitrite  that  certainly  takes  place,  its  molecular  weight  is  clearly 
indicated  as  106  rather  than  53. 

CcngiiHUion, — The  constitution  (HNO),  seems  to  be  excluded  by 
considerations  of  valency,  but  the  positive  evidence  for  (HON)^  is 
ample.  Zorn's  observation  that  ethylic  hyponitrite  decomposes  into 
nitrogen  and  alcohol  (and  aldehyde),  even  in  presence  of  reducing 
agents,  establishes  the  diazo-grouping  in  hyponitrites.  Ammonia  or 
other  amine  ^is  never  produced  in  the  decomposition  of  any  hypo- 
nitrite. Then  the  conversion  of  a  hydroxyamidosulphonate  into  hypo- 
nitrite affords  a  beautiful  demonstration  of  the  oxylic  constitution  of 
the  hyponitrites, 

2HO-NH-S08Na+  4NaOH  «  NaONINONa  +  2NaS03Na  +  4H2O. 
Hiantzsch  and  Sauer  have  also  given  an  equally  convincing  proof  of 
the  same  pointy  by  introducing  nitrosyl  into  dimethylhydroxycarb- 
amide  and  decomposing  the  product  by  alkali  (see  below).  The  facts 
that  cuprous  hyponitrite  cannot  exist,  and,  on  the  other  hand,  that 
the  mercurous  hyponitrite,  and  not  the  mercuric  salt,  is  stable,  point 
also  to  the  metals  being  united  to  the  oxygen,  and  not  to  the  nitrogen. 


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124  DIVERS:  HYPONITRITES ;   THEIR   PROPERTIES,   ETC. 

HantzBch  and  Sauer,  in  their  deBire  to  prove  that  nitramine  is  not 
H^N'NOg,  bat  a  stereoisomeride  of  hyponitrous  acid,  would  have  it 
that  their  interesting  formation  of  hyponitrous  acid  from  dimethyl- 
hydrozynitroBOcarbamide  is  analogous  to  that  of  nitramine  from 
nitroBourethane, 

EtO-OO(NjOjH)  +  HOH  =  H(Nj,02H)  +  EtO-OOOH ; 
lOf Oj-  C0(N,03H)  +  HOH  «  H(N,02H)  +  NMoj-  CXX)H  (decomposing). 
However,  by  displaying  what  (NjO^H)  conceals,  namely,  the  difference 
between  the  nitramine  and  the  isonitramine, 

Thiele.  Hantztch. 

EtO-00  -NH-NOjj,  or  EtO-00  'N;— ;N-  OH  +  H^O  -  NH^-NO^,  or 

HN— N-OH  +  Ac. 

NMoj-  CO-N(OH)NO  +  HjO  =  N(0H):N0H  +  Ac., 

it  becomes  evident  that  the  hydrogen  of  the  water  (or  metal  of  the 
alkali)  goes,  in  the  case  of  the  nitramine,  to  the  amidio  nitrogen  united 
to  the  carbonyl,  whilst,  in  the  case  of  the  isonitramine,  it  goes  to  the 
nitrozy-  or  nitroso-nitrogen  not  united  to  the  carbonyl,  even  if  Hantzsch 
and  Sauer's  free  resort  to  tautomery  could  be  justified.  Surely,  this 
difference  is  too  great  to  allow  of  nitramine  being  treated  as  a  probable 
or  actual  stereoisomeride  of  hyponitrous  acid.  Hantzsch's  formula, 
KO  'Nr^^N'  SOgK,  for  potassium (hypo)nitrososulphate  has  been  shown 

by  Haga  and  me  to  have  nothing  favouring  its  preference  to  that  of 
KO'NIN'O'SOgE,  which  has  so  much  to  be  said' for  it. 

Analogy  of  HyponUrites  to  Carhonatea — of  Nj  to  CO. — In  hardly 
forming  salts  with  the  feebler  metal  radicles,  such  as  aluminium  and 
f  erricum  j  in  decomposing  readily  into  anhydride  and  water ;  and  in 
having  its  soluble  normal  salts  with  very  alkaline  reaction,  hypo- 
nitrous acid  resembles  carbonic  acid,  as  was  indicated  in  my  first 
paper.  Zom,  also,  in  one  of  his  papers,  dwells  on  the  analogy  of  the 
one  acid  to  the  other,  pointing  out  that  the  salts  have  the  same 
moleoolar  magnitude,  since  Nj  and  00  are  both  28. 

As  is  well  known,  the  physical  properties  of  nitrogen  and  carbon 
monoxides  are  throughout  almost  identical.  The  radicles,  carbonyl 
and  dinitrogen,  also  are  both  bivalent,  and  occur  combined  with  ozylic, 
imidic,  and  alkyl  radicles.  Thus,  C0(0Na)2  and  COONa(OH)  find 
their  analogues  in  N2(ONa)2  and  N20Na(0H).  Just  as  ferric  oxalate, 
^«2(^2^2^2)s»  becomes  Fe2(C20302)2  +  2000,  so  ^g2Q^P%)%  becomes 
Hg2(N202)  +  2NO.  COO  corresponds  with  N^O ;  also  COINAg  to 
NjINAg.  Lastly,  ketonic  compounds  are  perhaps  represented  by 
azo-compounds. 

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KCPPINO  :  DEBIVATIV2S  OF  CAMPHORIC  ACID.     PART  lU.      125 


BtUiofftaphy*, 

H.  Davy,  Researches,  1800,  254 ;  Hess,  Ann,  Phys.  Chem.,  1828, 12, 
257  3  Pflouze,  Ann.  Chim.  Phys.,  1836,  [ii]  60, 151 ;  SchoenbieD,  J.pr. 
Cham.,  1861,  84,  202;  Be  Wilde,  Butt.  Ae.  Belg.,  1863,  [ii],  16,  560, 
and  Awn.,  1864,  SuppL,  3,  175 ;  Fremj,  dmpt.  rend.,  1870, 70, 66  and 
1208 ;  Maamen6,  Compi.  rend.,  1870,  70,  149 ;  /.  Ch.  Soc.,  1872,  26, 
772;  Ch.  Nms,  1872,  26,  153  and  285;  Th^<yrie  genh-ale  de  Vacti<m 
eUmiqus  (Paris:  Danod),  1880,^286;  Divers,  Proe.  Ray.  Soe.,  1871, 
10,  425  and,  in  part,  Ch.  News,  23,  206 ;  Ber.,  18^6,  29,  2324 ;  Ann., 
1897,  296,  366 ;  Divers  and  Haga,  J.  Ch.  Soc,  1884,  46,  78 ;  1885, 
47,  203  and  361 ;  Proc.  Ch.  Soc.,  1887,  3,  119 ;  J.  Ch.  Soc.,  1889, 66, 
760 ;  1896,  60,  1610 ;  Zorn,  Ber.,  1877, 10, 1306  ;  1878, 11, 1630  and 
3317 ;  1879,  12,  1509 ;  1882, 16,  1007  and  1258 ;  van  der  Pl^ttsi 
Ber.,  1877, 10,  1507 ;  Menke,  J.  Ch.  Soc.,  1878,  33,  401 ;  Berthelot 
and  Ogier,  Compt.  rend.,  1883,96,  30  and  84  ;  Bertbelot,  Compt.  rend., 
1889,  106,  1286 ;  Danstan  and  Dymond,  J.  Ch.  Soc.,  1887,  61,  646  ; 
Dunatan,  Proe.  Ch.  Sac.,  1887,  3,  121 ;  Maquenne,  Compt.  rend.,  1889, 
108,  1303;  Kolotow,  J.  ph.  Russ.,  1890,  23,  3;  Abstr.  in  Chem. 
Centr.,  1891,  i,  1859,  and  BuU.  Soc.  Chim.,  1891,  [iii],  6,  924 ;  Thorn, 
Inaug.  Diss.,  Prog.,  1893  and,  in  part,  Monaish.,  1893,  14,  294;  W. 
Widioenns,  Ber.,  1893,  26,  771 ;  Paal,  Ber.,  1893,  26,  1026 ;  D.  H. 
Jackson,  Proe.  Ch.  Soc,  1893,  9,  210 ;  Tanatar,  J.  Russ.  Ch.  Soc, 
1893,  [i],  26,  342;  Ber.,  Ref.,  763;  Ber.,  1894,  27,  187;  1896, 
29,  1039  ;  Hantzsch,  Ber.,  1896,  29, 1394 ;  Hantzsch  and  Kaufmann, 
Ann.,  1896,  292,  317;  Hantzsch  and  Sauer,  Ber.,  1898,  299,  67; 
Pfloty,  Ber.,  1896,  29,  1659;  BAy,  J.  Ch.  Soc,  1897,  71,  347,  1097, 
and  1105;  Kirschner,  Zeit.  anorg.  Chem.,  1898, 16,  424. 


XVI. — Derivatives  of  Camphoric  Acid.     Part  II L 

By  Febderio  Stanley  Kipping,  Ph.D.,  D.Sc.,  F.R.S. 

The  first  of  these  papers  on  derivatives  of  camphoric  acid  (Trans., 
1896,  69,  913)  contained  an  account  of  a  number  of  optically  active 
adds  and  other  compounds  which  had  been  obtained  from  ir-bromo- 
camfdioric  add,  in  the  course  of  attempts  to  open  the  closed  chain 
contained  in  this  simple  substitution  product  of  camphoric  acid  at  a 
different  point  from  that  at  which  it  is  broken  in  the  oxidation  of 
euDphoric  add,  the  parent  substance,  to  camphoronic  acid. 

The  prindpal  acids,  which  have  already  been  described,  were 
obtained  in  the  following  manner.  if-Bromocamphoric  acid  was  treated 
with  an  aUkali  and  thus  converted  into  (a)  tranfl^nssamphanio  add, 

VOL.  LXXV.  C^r\(^ci\o 

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126     KIPPINQ :  DERIVATIVES  OF  CAMPHOBICI  ACID.     PART  UL 

Cjo^i4^4>  a  monocarbozylio  acid  containing  a  lactone  ring,  and 
(5)  ir-hydrozycamphoric  acid,  Cj^H^gOg  ;  these  two  compounds  wero 
oxidised  by  nitric  acid  to  one  and  the  same  ^aiM-«M3amphotricarbozylic 
acid,  from  which  the  oa-isomeride  was  also  obtained. 

The  farther  oxidation  of  ^nsnf-Tr-camphotricarboxylic  add  being 
attended  with  considerable  difficulty,  owing  to  the  great  stability  of 
the  compound,  it  was  converted  into  its  monobromo-substitution  pro- 
duct and  the  latter  was  then  decomposed  with  water ;  in  this  way,  two 
isomeric  lactones  of  the  composition  OioHi^^^,  derived  from  a 
hydroxycamphotricarboxylic  acid,  O^QK^fi^,  were  obtained,  but  these 
derivatives,  like  the  parent  substance,  were  found  to  be  very  stable, 
and  could  not  be  made  to  yield  satisfactory  oxidation  products. 

Having  failed  to  obtain  any  easily  oxidisable  derivative  of  cam- 
phoric acid  by  these  means,  attempts  were  next  made  to  oxidise  cU-^r- 
camphanic  acid,  CjqHj^O^,  an  interesting  compound  obtained  by  the 
distillation  of  its  isomeride  ^an«^-camphanic  acid  ;  these  experiments 
were  successful  in  a  measure,  inasmuch  as  a  crystalline  hydroxy-ctfir- 
camphanic  acid  was  thus  obtained,  but  this  compound,  like  the  others 
just  mentioned,  effectually  resisted  further  oxidation. 

It  will  be  seen  from  this  brief  statement  that  the  main  object  of 
this  investigation  had  been  defeated  by  the  stability  of  these  different 
substitution  products  of  camphoric  acid,  all  of  which  still  contained  the 
closed  chain  of  the  parent  substance ;  moreover,  the  difficulty  of 
obtaining  material  sufficient  for  oxidation  experiments  on  the  large 
scale  rendered  it  almost  impossible  to  proceed  further  on  these  lines. 
It  was  necessary,  therefore,  to  try  and  attack  the  ir-bromocamphoric 
acid  in  a  somewhat  different  manner,  namely,  to  convert  it,  if 
possible,  into  a  dibromo-compound,  and  then  to  substitute  hydroxyl 
for  one,  or  both,  of  the  bromine  atoms,  and  thus  obtain  in  a  more  direct 
manner  a  substitution  product  which  might  be  oxidisable. 

The  results  of  these  experiments  are  described  in  this  paper. 

When  ir-bromocamphoric  acid  is  brominated,  it  is  converted,  in 
almost  theoretical  quantities,  into  a  substance  of  the  composition 
CioHi2^^2^s>  which,  for  reasons  given  later,  is  named  vw  *-dibromocam- 
phoric  anhydride ;  this  substance  crystallises  in  magnificent  rhombic 
plates,  and  on  hydrolysis  with  concentrated  nitric  acid  it  is  trans- 
formed into  nw-dUn'omocamphoric  acid,  C^QH^^Br^O^,  a  substance  which 
in  many  respects  is  very  similar  to  ir-bromocamphoric  acid  and  other 
halogen  derivatives  of  this  compound  which  have  been  described 
(compare  Lapworth  and  Kipping,  Trans.,  1897,71,  15). 

nt^Dibromocamphoric  acid  is  decomposed  when  it  is  heated  alone  or 
with  water,  yielding  hydrogen  bromide  and  an  acid  of  the  composition 

*  The  letter  w  has  been  previonaly  med  to  denote  a  certain  pocition  in  the 
molecale  of  camphoric  acid  (compare  Trana.,  1898  69i  61,  and  916). 

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KIPPING:  BfiRIVATiyJSS  OF  OAMPfiOEIC  ACIl>.     PART  IIL     127 

C|^j3Br04,  which,  from  its  method  of  formation,  must  be  regarded  as  a 
lactonic  monooarbozylie  add ;  for  this  and  other  reasons,  this  compound 
is  named  w^^iromO'VHXifnphanic  add.  It  crystallises  in  orthorhombic 
prisms,  and  both  its  amid€^  CgHi^BrO^'OO'NH,,  and  msihylio  salt, 
OgH^^rO^-OOOMe,  are  well-defined  compounds. 

When  x>bromo-tCHiamphanic  acid  is  treated  with  alkalis,  it  yields  a 
crystalline  product  which  is  identical  with  hydroxy-cie-n^camphanic 
acid,  the  oxidation  product  of  cta-vcamphanic  acid ;  this  hydroxy-acid 
is  also  formed  by  the  action  of  excess  of  alkali  on  nto-dibromocam- 
phoric  anhydride.  When,  on  the  other  hand,  ^r^bromo-u^camphanic 
acid  is  boiled  with  nitric  acid  and  silver  nitrate,  it  is  converted  into  a 
compound  of  the  composition  O^qH^jO^  which  is  identical  with  one  of 
the  iiM>meric  lactones  of  hydroxycamphotricarboxylic  acid. 

These  transformations,  the  chemical  properties  of  the  various  com- 
pounds, and  the  relations  existing  between  these  and  other  substitu- 
tion products  of  camphoric  acid,  can  only  be  elucidated  by  making  use 
of  some  structural  formula  for  camphoric  acid,  and  in  previous  papers 
Bredt's  formula  was  employed  because  it  accounted  for  all  the  facts 
ondmr  discussion  in  a  satisfactory  manner,  and  at  the  same  time 
seemed  to  have  more  evidence  in  its  favour  than  any  other  of  the 
many  formuln  which  had  then  been  suggested.  The  recent  publica- 
tion of  an  important  paper  by  W.  H.  Perkin,  junr.  (Trans.,  1898,  73, 
796),  in  which  a  new  formula  for  camphoric  acid  is  propounded,  ha» 
certainly  necessitated  a  modification  of  this  last  statement ;  never- 
theless, the  difference  between  Bredt's  and  Parkin's  formulee  is  of  such 
a  kind  as  to  require  little,  if  any,  alteration  in  the  views  which  have 
been  advanced  in  explaining  the  relationship  of  these  ir-derivatives. 

On  inspection,  it  will  be  seen  that  these  two  f ormulsB,  which  are 
given  below,  differ  merely  in  this;  namely,  that  one  of  the  >'CH.j 
groups  in  Bredt's  is  transferred,  in  Perkin's  formula,  to  a  position 
between  the  >OMej  and  >OH*OOOH  groups. 


8 

COOII 


Bredt  Perkin. 

This  change  does  not  effect  any  of  the  author's  previous  arguments, 
which  were  mainly  based  on  stereochemical  considerations,  and,  iti 
£act»  only  makes  this  difference,  that  the  ir^amphanic  acids,  according 
to  Perkin's  formula,  may,  but  do  not  necessarily,  contain  a  8-  instead 
of  a  y-lactone  ring. 

K  2 

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l28      letlI»l>INa:  DERlVATtVtiS  OF  CAMPHDBIC  ACID.     PABt  IIL 

Making  use,  then,  of  Perkin's  formula,  and  representing  v-bromo- 
camphoric  acid  by  I  (below),  the  substitution  of  bromine  for  hydrogen 
would  afford  a  dibromocamphoric  acid  which  must  be  represented  by 
formula  II,  because  in  the  formation  of  this  substance  the  bromine 
doubtless  displaces  the  same  tertiary  hydrogen  atom  as  that  which  is 
expelled  in  the  formation  of  to-bromocamphoric  anhydride  from 
ordinary  camphoric  acid. 

CH,— C<CB^^  CH,— CK^^H 

L  r-Bromocamphoric  acid*  11.  ino-Dibromocamphoric  acid. 

ir^Bromo-tiMiamphanic  acid,  which  is  formed  from  the  dibromo-acid 
with  the  greatest  readiness,  just  as  to-camphanio  acid  is  very  easily 
produced  from  to-bromocamphoric  acid,  might  be  represented  by  one  of 
several  isomeric  formuln,  of  which,  however,  it  is  unnecessary  to  give 
examples,  as  it  is  possible  to  select  the  most  probable  one  from  a  con- 
sideration of  the  following  facts  and  arguments.  In  the  first  place, 
there  are  strong  grounds  for  supposing  that  the  v^bromine  atom, 
namely,  that  which  is  a  constituent  of  the  -OHjBr  group,  is  still 
present  in  this  bromocamphanic  acid,  because  it  is  known  that  the 
to-bromine  atom  in  lo-bromocamphoric  acid  is  very  easily  eliminated 
as  hydrogen  bromide  by  the  action  of  boiling  water,  whereas  «^bromo- 
camphoric  acid  is  comparatively  stable  under  these  conditions ;  in  the 
second  place,  the  bromocamphanic  acid  in  question  offers  considerable 
resistance  to  the  attack  of  oxidising  agents,  whereas  had  it  been 
formed  by  the  elimination  of  the  n^bromine  atom,  it  should  resemble 
fratMircamphanic  acid  in  behaviour  and  be  easily  oxidisable  to  a 
bromo-tricarboxylic  acid. 

A  comparatively  simple  way  of  settling  this  question  as  to  which 
of  the  two  halogen  atoms  is  eliminated  from  the  dibromo-acid  offered 
itself,  namely,  to  prepare  a  ir-bromo-to-chlorocamphoric  anhydride  by 
chlorinating  the  ir-bromo-acid,  and  then  to  convert  this  substance  into 
the  substituted  camphanic  acid  by  treatment  with  boiling  water.  On 
making  these  experiments,  it  was  found  that  the  Tr-bromo-uhehlarO' 
camphoric  anhydridcy  C^oHj^BrClOg  was  readily  acted  on  by  boiling 
water  with  formation  of  hydrogen  chloride  and  a  bromocamphanic 
acid  identical  with  that  obtained  from  the  dibromoan hydride.  It 
follows,  therefore,  that  the  bromo-acid  in  question  is  a  ir-bromo-to- 
camphanic  acid,  and  its  constitution  mny  be  expressed  by  one  of  the 
following  stereoisomeric  formulae.  ^ 


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KIPPING  :  BERIYATIVES  OF  CAMPHORIC  ACID.      PART  III.      129 


CHj. 


CH, 


^Njooh 


III.  v-Bromo-cw-i£^-camphaDic  aoid.     lY.  ir<Bromo<^ra7W-i0-cainphanic  aoid. 

Now  it  seems  probable  that  the  first  of  these  two  fornmlso  repre* 
sents  the  configuration  of  the  acid  better  than  does  the  second,  in  spite 
of  the  fact  that  this  view  necessitates  the  assumption  that  intramole- 
cular change  occurs  in  the  formation  of  the  acid  from  ntc-dibromo- 
camphoric  anhydride ;  when  the  properties  of  ordinary  icMUtrnphanic 
acid  are  considered,  it  must  be  admitted  that  this  compound  is  probably 
a  eiff-lactonic  acid,  because  the  hydrozy-acid,  of  which  it  forms  salts 
on  treatment  with  alkalis,  is  net  known  in  the  free  state,  but  immedi- 
ately passes  into  its  lactone ;  tiMiamphanic  aqid,  therefore,  is  doubtless 
stereochemically  analogous  to  cia-Tr-camphanic  acid,  whereas  the  trans- 
iiMsamphanic  acid,  corresponding  with  the  unstable  ^raTM-ir^camphanic 
acid,  has  not  yet  been  prepared. 

It  is  probable,  then,  that  when  lo-bromocamphorio  anhydride  is 
converted  into  to-camphanic  acid,  the  carbozyl  group  changes  its 
position  stereochemically,  just  as  it  is  known  to  do  to  a  considerable 
extent  in  the  reduction  of  t£^•bromooamphoric  anhydride,  a  reaction 
which  affords  a  mixture  of  ois-  and  trana-y  or  d-  and  <^iso-camphorio 
adds  (Aschan,  Ada  Soe.  Seimt.f&nn.^  21,  [v],  p.  195). 

The  conclusion  thus  arrived  at,  namely,  that  T-bromocamphanic 
aeid  has  the  configuration  represented  by  formula  III,  is  in  accord- 
ance with  the  behaviour  of  this  substance,  and  also  accounts  for  its 
conversion  into  hydroxy-ci«-«^-camphanic  acid;  when  treated  with 
potash,  it  may  be  supposed  that  it  first  gives  a  salt  of  to-hydroxy-ir- 
bromocamphoric  acid,  the  tr-lactone  ring  undergoing  hydrolysis,  and 
that  then  potassium  bromide  is  eliminated  with  formation  of  a  different 
lactone  ring,  namely,  that  which  is  contained  in  ciairoamphanic 
add. 


CH,. 


CHj 


^<COOH 


T.  vBromo-CM-te-KwnphaDic  acid.      YI.  li^-Hydrozy-cM-r-camphanic  acid. 

The  last  formula  (YI)  indicates  the  possible  existence  of  a  dUactane, 
which  would  be  derived  from  hydroxy-cis-ir-camphanic  acid  by  the 
eUmination  of  one  molecule  of  water  from  the  remaining  -OH  and 


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130      KIPPING:  DERIVATIVES  OF  CAMPHORTC  ACID.      PART  UI. 

-OOOH  groups ;  although  the  isolation  of  such  a  substance  has  not 
yet  been  accomplished,  indications  of  its  formation  have  been 
observed,  and  the  neutral  crystalline  compound  obtained  by  bromina- 
ting  trontf-ir-camphaQic  acid  (Trans.,  1896^  60,  934),  or  the  neutral 
oily  product  formed  in  the  decomposition  of  iruMiibromocamphorio 
anhydride  (see  later),  may  possibly  be  a  compound  of  this  kind  ;  it  is 
by  no  means  improbable,  however,  that  the  existence  of  one  lactone 
ring  may,  owing  to  stereochemical  causes,  hinder  the  formation  of  a 
second  one,  and  thus  render  it  difficult  to  obtain  such  a  dilactone  by 
ordinary  methods. 

The  farther  oxidation  of  the  compounds  obtained  from  dibromo- 
camphoric  anhydride  has  not  yet  been  accomplished  with  satisfactory 
results  in  a  single  case;  to  give  an  instance  of  the  difficulty  of 
oxidising  some  of  these  products,  it  may  be  mentioned  that  a  small 
quantity  of  the  lactone  of  i&-hydroxycamphotricarboxylic  acid  may 
be  heated  at  100°  with  a  mixture  of  concentrated  nitric  and  hydro- 
chloric acids,  or  with  a  mixture  of  concentrated  nitric,  and  sulphuric 
acids,  and  after  several  hours  treatment,  the  lactone  is  deposited 
unchanged  on  keeping  the  solution  at  ordinary  temperatures. 

Most  of  the  compounds  described  in  this  paper  are  readily  obtain- 
able in  well-defined  crystals,  and  the  author  has  again  to  express  his 
thanks  to  Mr.  W.  J.  Pope  for  a  number  of  interesting  reports  on  the 
crystallographic  characters  of  the  various  substances  which  have  been 
submitted  to  him  for  examination. 

Part  of  the  cost  of  this,  and  of  all  the  other  investigations  on  cam- 
phor derivatives,  which  have  been  published  by  the  author,  alone  and 
in  conjunction  with  Mr.  W.  J.  Pope  and  Dr.  A.  Lapworth,  has  been 
defrayed  by  grants  from  the  Koyal  Society,  for  which  the  author  desires 
to  express  his  thanks  to  the  €k)vemment  Grant  Oominittee. 

EXPEBIMENTAL. 

vuhDibramoeamphonc  Anhydride^  CgHigBrg^^^^O. 

Dry  9r-bromocamphoric  acid  (Trans.,  1896,  60,  924),  which  has  been 
freed  from  a-nitro-air-dibromocamphor  by  washing  with  chloroform, 
is  ground  up  with  about  one-tenth  of  its  weight  of  amorphous  phos- 
phorus, and  gradually  treated  with  bromine  in  a  Wiirtz  flask ;  when 
the  first^gorous  action  has  subsided,  the  flask  is  heated  on  a  water- 
bath  and  the  addition  of  bromine  continued  very  slowly,  so  that  the 
quantity  added  in  the  course  of  about  3  hours  is  approximately  twice 
the  weight  of  the  acid  taken.  During  this  operation,  the -evolution 
of  hydrogen  bromide  gradually  slackens  but  without  ceasing  entirely, 
and  bromine  also  escapes  in  small  quanttti^^'  ^  ^^^  ^^^  ^^^  ^^  ^^ 

ninitiypri  H.i  V  llOOO  I  P 


KIPPIHG:  DERIVATIVES  OP  CAMPHORIC  ACID.      PART  III.      ISl 

normal  reaction  is  difficult  to  recognise.  The  excess  of  bromine 
having  been  expelled,  the  product,  which  consists  of  a  red,  crystalline 
mass,  saturated  with  a  red  oil,  is  well  agitated  with  successive  small 
quantities  of  cold  water,  and  then  with  a  little  cold  dilute  alcohol ; 
iheee  liquids  remove  most  of  the  oily  impurity,  leaving  a  pale  reddish 
or  greenish  crystalline  product,  the  weight  of  which  is  rather  greater 
than  that  of  the  original  add,  the  average  yield  amounting  to  about 
90  per  cent,  of  the  theoretical.  A  small  quantity  of  a  crystalline  bye- 
prodnct  is  obtained  from  the  alcoholic  washings,  but  the  examination 
of  this  substance  is  not  completed. 

The  crude  anhydride  is  very  easily  purified,  without  appreciable 
loss,  by  dissolving  it  in  boiling  chloroform,  and  precipitating  the 
filtered  solution  with  ether,  repeating  these  operations  if  necessary  ; 
a  sample  thus  purified  and  dried  over  sulphuric  acid  was  analysed. 

01779  gave  02307  CO,  and 0-0643 Kfi.  0  =  35-36;  H  =  401. 

01248    „    0-1426  AgBr.     Br » 47*8. 

O^oHi^rjOj  requires  0  =  35-29 ;  H  «  3-62 ;  Br  -  4706  per  cent. 

Dibromocamphoric  anhydride  is  readily  soluble  in  boiling  chloro- 
form, from  which  it  crystallises  in  large,  transparent  plates  (see 
below)  melting  at  209 — 210°*;  it  is  also  readily  soluble  in  boiling 
eihylic  acetate,  acetic  acid,  and  cold  acetone,  moderately  in  cold 
benxene,  and  sparingly  in  cold  ether  and  alcohol  It  sublimes  readily 
when  heated  in  a  test-tube,  giving  a  solid  sublimate  of  lustrous  prisms. 
It  seems  not  to  be  acted  on  by  boiling  quinoline,  from  which  it  separates 
again  on  cooling,  but  when  heated  with  aniline  it  is  vigorously 
attacked;  it  dissolves  in  warm,  concentrated,  sulphuric  acid  with 
evolution  of  hydrogen  bromide,  and  on  heating  more  strongly  the 
solution  darkens  in  colour  considerably. 

Bailing  water  slowly  converts  the  anhydride  into  bromocamphanic 
aeid  and  hydrogen  bromide,  and  a  boiling  solution  of  half  a  molecular 
proportion  of  sodium  carbonate  in  dilute  alcohol  brings  about  a 
OBiilar  change ;  boiling  alcoholic  or  aqueous  potash  in  eJccess  causes 
the  elimination  of  both  the  bromine  atoms  with  formation  of  the 
potassinm  salt  of  hydroxy-cwir-camphanic  acid  or  dihydroxycamphoric 
add.  Fusion  with  potash  at  a  moderately  low  temperature  also 
resnltB  in  the  formation  of  a  salt,  from  which  u^hydroxy-cu^-cam- 
phanic  acid  is  liberated  on  the  addition  of  a  mineral  acid,  but  other 
producte  appear  to  be  formed  in  small  quantities.  When  silver 
nitnte  is  added  to  a  solution  of  the  dibromo-anhydride  in  acetic  acid, 
the  separation  of  silver  bromide  soon  commences,  and  after  prolonged 
bmling  io-hydroxy-«isirH»mphanic  acid  can  be  isolated  from  the  isolu- 
ticm;  the  y-lactone  of  hydroxycamphotricarboxylic  acid  (Trans.,  1896, 

*  for  coRoetunis  to  be  applied  to  these  qielting  points,  see  Tians.,  1697,  71,  968, 

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132     KIPPING:  DEBIYATITES  OF  CAMPHORIC  ACID.     PABT  in. 


60y  961)  also  seems  to  be  produced  under  these  conditions  by  the 
oxidation  of  the  dihydroxycamphoric  acid,  which  is  probably  formed 
as  an  intermediate  product^  but  the  isolation  of  the  lactone  is  not 
very  easy. 

Dibromocamphoric  anhydride  is  ladvorotatory.  For  the  determina- 
tion  of  its  specific  rotation,  a  solution  in  chloroform  of  1*158  grams 
was  diluted  to  25  cc,  and  examined  at  14°  in  a  200  mm.  tube ;  the 
mean  of  7  obseryations  gave  a=  -2*9%  from  which  [a]pa  -31"2°.* 

The  following  is  Mr.  W.  J.  Pope's  account  of  the  crystals  of  the 
dibromo-anhydride,  which  were  obtained  by  spontaneous  evaporation 
of  its  solution  in  chloroform. 

''  ffti^-Dibromocamphoric  anhydride  crystallises  in  transparent^  rhom- 
boidal-shaped,  orthorhombic  plates  (Fig.  1)  possessing  a  calcite-like 
lustre.  The  dominant  form  is  always  the  pinacoid  a{100},  and  the 
form  ^{011}  is  usually  the  next  largest ;  these  two  forms  give  fairly 
good  reflections.  The  prism  |7{1 10}  is,  as  a  rule,  much  smaller  than 
^{011},  and  the  pinacoid  5(010}  is  generally  very  small;  the  form 
r{101 }  is  always  small  but  bright,  and  is  frequently  absent. 

Fio.  1. 


"  Crystalline  system. — Orthorhombic. 

a:  6  :c«  1*4844: 1:0-7083. 
«  Forms  observed.— a{  100},  6{010},  p{UO},  ^{011},  r{101}. 

''  The  following  measurements  were  obtained. 


Angle. 

Number  of 
observations. 

Tiimtts. 

Mean. 

CUonkted. 

ap=lOO:nO 

84 

66'44'—  6617' 

66*2' 

|y=110:Il0 

18 

67  81  —  68  12 

67  54 

67*56' 

5^=010:110 

29 

88  80-- 84  24 

88  59 

88  58 

jrjr  =  011:0lT 

6^=010:011 

24 

109    1—109  40 

109  24 

109  28 

29 

54  28  —  54  59 

54  41 

54  41  80" 

99=011:011 

87 

7014—  70  54 

70  87 

,^ 

or=100:101 

18 

64    8—64  51 

64  27 

64  29  80 

rr=101:I01 

26 

50  47  —  51  86 

51    2 

51    1 

*  The  polfliimeter  used  in  these  determinations  coidd  only  be  read  to  6',  and 
the  results  may  not  be  rery  fu)cnr$t9i 


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KiPFDra:  DXRiYATnrn  of  camphoric  acid,    part  in.    13S 

**  The  faces  of  the  3M>ne  [001]  are  striated  with  lines  parallel  to  the 
(;  these  lines  are  sufficiently  well  developed  as  frequently  to 
disturb  the  measurements  in  that  zone.  The  optic  axial  plane  is 
0(001),  and  the  azia-6  is  a  bisectrix  of  negative  double  refraction ; 
the  optic  axial  angle  is  very  large,  but  the  h-hxis  is  probably  the  acute 
bisectrix*  There  is  a  fairly  good  cleavage  on  a{100},  and  the  cleavage 
faces  are  usually  marked  by  the  striations  noted  above ;  it  is  note- 
worthy that  the  crystals  are  always  tabular  on  a{100}. 

**  After  melting  on  a  microscope  slide  under  a  cover  slip  in  the  usual 
way,  the  substance  solidifies  readily  to  a  cubic  modification ;  when  the 
plate  cools  to  about  60°,  this  changes  to  a  doubly  refracting  biaxial 
modification  made  up  of  large  individual  fragments  which,  as  cooling 
eontinues,  crack  across  perpendicularly  to  their  long  directions.  The 
pieces  are  frequently  perpendicular  to  an  optic  axis,  and  are  marked 
by  interlaced  straight  striations.  The  double  refraction  seems  to  be 
of  negative  sign,  and  the  modification  is  in  all  probability  with  the 
crystals  measured  above." 

vuhDibromooamphorie  Aeid^  CJB.i2'Br^{000B)^ 

It  has  been  shown  in  previqus  papers  that  when  an  anhydride 
cannot  be  converted  into  the  corresponding  acid  by  treatment  with 
alkalis  or  with  boiling  water,  owing  to  elimination  of  the  elements  of 
a  halogen  acid,  as,  for  example,  in  the  case  of  the  anhydrides  of 
«9-bromocamphoric  acid  (Trans.,  1896,  69,  1),  ir-bromooamphoric  add 
(Trans.,  1896,  69,  927),  and  ir-chlorocamphoric  acid  (Lapworth  and 
Kipping,  Trans.,  1897>  71,  1),  this  conversion  is  easily  accomplished 
by  using  concentrated  nitric  acid  as  the  hydrolysing  agent.  This 
method  can  be  applied  with  very  satisfactory  results  for  the  prepara- 
tion of  dilvomocamphoric  acid  from  its  anhydride. 

Dibromocamphoric  anhydride  dissolves  readily  in  hot,  concentrated 
nitric  acid  (sp.  gr.  1*4),  and  if  the  solution  be  cooled  after  heating 
during  a  few  minutes  only,  most  of  the  anhydride  is  deposited 
uncfaaDged ;  if,  however,  the  nitric  acid  solution  be  heated  on  a  water- 
bath  in  an  evaporating  dish,  crystals  of  the  dibromo-acid  begin  to 
separate  after  a  short  time,  neither  nitrous  fumes  nor  bromine  being 
evolved  in  any  appreciable  quantity.  When  most  of  the  nitric  acid 
has  evaporated,  a  Uttle  water  is  added  to  precipitate  the  rest  of  the 
dibromo-acid,  and  the  colourless  crystals  are  then  separated- and  dried 
in  the  air.  This  product  is  generally  free  from  anhydride,  but 
should  the  latter  be  present,  it  is  easily  removed  by  washing  the 
erjstals  with  a  little  cold  chloroform,  in  which  the  acid  is  insoluble, 
orneariy  so. 


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134      KIPPINO :  DEBIVATIVE8  OP  OAHPHORIC  ACIIX      PART  IIL 

For  analysiB,  a  sample  was  treated  in  this  way,  and  then  recrystal- 
Used  from  ether  and  dried  at  100^  until  constant  in  weight. 

01682  gave  02076  CO,  and  0062i  H^O.     C  =  3366 ;  H  =  412. 
CioHj^BrjjO^  requires  C  =  33-62  ;  H  -  391  per  cent. 

mo-Dibromocamphorio  acid  crystallises  from  ether,  in  which  it  is 
very  readily  Boluble,  in  microscopic,  fouiveided  plates;  it  dissolves 
freely  in  cold  acetone,  ethylic  acetate,  and  methylic  alcohol,  but  is 
almost  insoluble  in  benzene  as  well  as  in  chloroform.  It  melts  at 
about  210°,  effervescing,  owing  to  the  escape  of  water  vapour  and 
hydrogen  bromide,  and  becoming  slightly  brown,  but  like  «o-bromo- 
camphoric  acid  and  all  the  «^halogen  derivatives  of  camphoric  add,  it 
is  stable  at  100°,  and  does  not  lose  in  weight  even  after  having  been 
heated  during  several  hours.  It  is  practically  insoluble  in  boiling 
water,  although  just  sufficiently  soluble  to  impart  to  the  water  an 
acid  reaction  after  heating  for  a  few  minutes ;  it  is  probable,  however, 
that  the  dibromo-acid  does  not  dissolve  unchanged,  and  that  the 
acidity  of  the  solution  is  due  to  hydrobromic  and  v-bromocamphanic 
acids,  since  these  two  compounds  are  rapidly  produced  when  a  solution 
of  the  dibromo-acid  in  dilute  methylic  alcohol  is  boiled. 

Hot  concentrated  nitric  acid  dissolves  dibromocamphoric  acid  freely, 
and  on  cooling  beautiful,  transparent,  flat,  four-sided  crystals  axe 
deposited,  but  they  are  not  large  enough  to  be  suitable  for  goniometric 
examination.  The  acid  dissolves  in  dilute  sodium  carbonate,  forming 
apparently  the  corresponding  sodium  salt,  as  on  acidifying  a  freshly 
prepared  solution  with  a  mineral  acid,  dibromocamphoric  add  is  repre- 
cipitated ;  when,  however,  such  a  solution  of  the  acid  is  boiled  for  a 
few  minutes  and  then  addified,  crystals  of  ir-bromocamphanic  add  are 
depodted,  hydrogen  bromide  having  been  eliminated. 

When  dibromocamphoric  acid  is  heated  in  a  test-tube  over  a  small 
flame,  it  first  melts  with  effervescence  and  then  distils,  charring  very 
slightly  but  evolving  hydrogen  bromide,  and  apparently  traces  of 
carbonic  anhydride;  the  crystalline  distillate  consists  of  a  mixture  of 
vtr-dibromocamphoric  anhydride  and  an  add  melting  at  176°,  whidi  is 
doubtless  ir-bromoeamphanic  add. 

No  attempts  were  made  to  prepare  salts  of  the  dibromo-add,  on 
account  of  the  readiness  with  which  it  is  decomposed  by  water,  alkali 
carbonates,  and  alkalis.  It  is  interesting  to  note  the  relative  stability 
of  hot  solutions  of  the  acid  in  concentrated  nitric  acid  and  in  water 
respectively ;  whereas  the  former  may  be  heated  during  several  hours 
without  suffering  any  appreciable  change,  dimination  of  hydrogen 
bromide  takes  place  rapidly  in  the  aqueous  solutions ;  this  bd|i^yioi|r 
is  similar  to  that  of  ir-bromocamphoric  add, 

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KIPPING  :   DERIVATIVES  OF  CAMPHORIC  ACID.      PART  HI.      136 

T-Bromo-to-Moroeamphorie  Anhydride,  OgHj^BrCl^^O^O, 

The  object  of  preparing  this  compoand  has  already  been  stated ;  the 
method  was  the  following.  Dry  powdered  ir-bromocamphoric  acid  was 
treated  with  a  slight  excess  of  the  theoretical  quantity  of  phosphorus 
pentachloridei  the  colourless  liquid  product  heated  on  a  water-bath, 
and  dry  chlorine  slowly  bubbled  into  it  for  about  4  hours,  or  until  the 
evolution  of  hydrogen  chloride  almost  ceased.  The  pale  yellow  oil 
thus  obtained  was  gradually  treated  with  ice  cold  water,  whereon  it 
quickly  solidified,  and  was  then  purified  by  washing  with  water  and 
dilute  alcohol  successively ;  for  analysis,  a  sample  was  recrystallised 
twice  from  chloroform  and  then  dried  over  sulphuric  acid. 

01576  gave  0-2349  CO, and  00602  HjO.    C  =  40-66  ;  H  =  4-24. 
CjoHjs^lBrO^  requires  C » 40*62  ;  H « 406  per  cent. 

s^Bromo-i9-ehlorocamphoric  anhydride,  like  the  corresponding  di- 
bromo-compound,  crystaJlises  best  from  chloroform,  from  which  it  is 
deposited  in  lustrous  prisms  (see  later)  melting  at  214 — 216^,  or  6^ 
higher  than  its  analogue ;  a  mixture  of  the  dibromo-  and  chlorobromo- 
anhydrides  shows  no  sign  of  melting  until  the  temperature  rises 
to  209 — 210° — the  melting  point  of  the  former — an  indication  of 
the  isomorphism  of  the  two  compounds  which  was  confirmed  by 
the  crystallographic  examination  made  by  Mr.  W.  J.  Pope  (see 
p.  136). 

In  most  respects,  the  properties  of  s-bromo-u^-chlorocamphoric  anhy- 
dride are  so  similar  to  those  of  the  corresponding  dibromo-compound 
that  further  description  is  unnecessary,  but  one  rather  interesting 
difference  in  behaviour  may  perhaps  be  noted.  When  the  chlorobromo- 
eompound  is  crystallised  from  a  mixture  of  chloroform  and  ether,  it  is 
sometimes  deposited  in  long,  slender  prisms,  or  needles,  as  well  as  in 
the  compact  prisms  already  referred  to ;  these  two  kinds  of  crystals 
differ,  not  only  in  appearance,  but  also  in  behaviour,  as  the  former 
become  opaque  when  kept  over  sulphuric  acid  or  heated  on  a  water- 
bath,  whereas  the  latter  remain  transparent ;  both  forms,  however, 
melt  at  214— 215^ 

Experiments  showed  that  the  needles  are  formed  when  the  crystal- 
lisation of  the  ethereal  chloroform  solution  takes  place  at  low 
temperatures,  as,  for  example,  at  -  6°,  whereas,  when  the  solution 
is  kept  at  about  the  ordinary  atmospheric  temperature,  one  or  other, 
or  both  forms  may  be  deposited ;  ethereal  chloroform  solutions  of  the 
dibromo-anhydride,  crystallised  at  temperatures  just  below  0°,  did  not 
deposit  anything  but  the  rhombic  prisms  described  above. 

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136      KIPPING:  DERIVATIVES  OF  CAMPHORIC  ACID.     PART  III. 

This  anhydride,  like  the  corresponding  dibromo-compound,  is  l»vo- 
rotatory  ;  a  solution  of  1*1 5«3  grams  in  chloroform  dilated  to  25  cc, 
and  examined  at  14^  in  a  200  mm.  tube,  gave  a  »  -  2*4°  as  the  average 
of  seven  observations  :  hence  [a]D==  -  26*1°.* 

"  irt/7-Chlorobromocamphoric  anhydride  crystallises  in  large,  trans- 
parent, orthorhombic  prisms  (Fig.  2),  which  appear  rather  more  lostrotts 
than  the  crystals  of  the  corresponding  dibromo-compound.  The 
dominant  form,  as  in  the  latter  case,  is  usually  the  pinaooid  a{100}, 
but  the  form  j^jlOO}  is  sometimes  the  most  developed ;  the  pinacoid 
5{010}  is  also  usually  well  developed,  and  ^{011}  is  generally  broader 
than  in  dibromocamphoric  anhydride.  The  crystals  of  the  latter 
give  much  better  results  on  measurement  than  do  those  of  the  com- 
pound now  described. 

Fig.  2. 


^1 

"A 

1 

\ 

yT--    ! 

V 

\ 

/•[ 

r 

» 

f 

i 

,^/ 

•*  Crystalline  system. — Orthorhombic. 

a  :6:c  =  1-4789  :1:0-7107. 
"Forms  observed  :  a{100},  6{010},  je){110},  ^{011},  r{101}. 

''  The  following  measurements  were  obtained. 


Angle. 

Number  of 
observations. 

LimiU. 

Mean. 

Calculated. 

ap=100:110 
pp=110:I10 
6p=010:110 
W=  Oil:  Oil 
Sg=010:011 
gj=011:0il 
ar=100:101 

47 
32 
21 
88 
43 
44 
13 

65''  1'—  66'64' 
07  49—  69    2 
33  20  —  34  48 
108  42  -109  67 
63  89—  66  10 
69  67  —  71  28 
63  19—66    6 

66*66' 
68  31 
34    7 
109  16 
64  38 
70  48 
64  24 

68**  8' 

34    4 

109  12 

.64  S« 

64  20 

'<  The  forms  in  the  zone  [001],  and  more  especially  the  pinacoid 
a{100},  ave^'^arked  with  striations  parallel  to  the  c-axis.  The  optic 
axial  plane  is  c{001},  and  the  axis  h  is  the  acute  bisectrix  ;  the  double 

*  Compare  footnote,  p,  182. 


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^l^PIKG:  DERIVATIVES  O^  CAltPHOBIO  ACID.     PART  ttl.      137 

refraction  is  negative  in  sign,  and  the  optic  axial  angle  is  large. 
There  is  a  very  poor  conchoidal  cleavage  on  a{100}. 

''After  melting  on  a  microscope  slide  under  a  cover  slip,  the  com- 
pound solidifies  readily,  yielding  a  singly-refracting  cubic  modification ; 
this,  before  it  cools  to  the  atmospheric  temperature,  changes  to  a 
biaxial  doubly-refracting  modification,  which  is  formed  in  large  plates 
very  similar  to  those  constituting  the  film  of  the  corresponding 
dibromo-derivative.  These  plates  are  marked  with  interlaced,  straight 
striations,  and  are  frequently  perpendicular  to  an  acute  bisectrix  of 
large  axial  angle  and  of  negative  double  refraction. 

'*  As  would  be  expected  from  the  chemical  relationship  between  the 
two  compounds,  uto-dibromo-  and  iruHshlorobromo-camphoric  anhydride 
are  isomorphous;  the  axial  ratios  are  of  the  same  order  and  cor- 
responding angles,  as  shown  in  the  following  table,  do  not  differ 
greatly  in  the  two  cases. 


CioHuBr,0,. 

CioHijClBrO,. 

Differences. 

alh 

1-4844 

1-4789 

+  0-0055 

e/b 

0-7083 

0-7107 

-0-0024 

ilc 

2-0958 

2-0809 

+  0-0149 

ap=100:110 

56*2' 

55'56' 

+  0*6' 

6p=^010:110 

33  58 

84    4 

-06 

fly=001:011 

35  18  30" 

35  24 

-0580* 

59=010:011 

54  41  80 

64  36 

+  0  5  80 

ar=.100:10I 

64  20  80 

64  20 

+  0  9  30 

€r=001:101 

25  30  30 

25  40 

-0930 

"  It  will  be  seen  that  the  dimensions  measured  in  the  zone  [001] 
differ  least  in  the  two  cases,  whilst  those  in  the  parametral  zone  [010] 
exhibit  the  greatest  differences.  The  same  forms  are  present  on 
crystals  of  both  anhydrides  and  striations  parallel  to  the  zone  axis 
observed  in  the  zone  [001]  are  also  observed  in  both  cases. 

*'  Amongst  the  differences  may  be  noted  that  the  crystals  of  the 
dibromo-compound  show  a  much  better  cleavage  parallel  to  {100}  than 
do  those  of  the  chlorobromonlerivative ;  again,  the  crystals  of  the 
former  are  really  much  better  developed  and  give  more  trustworthy 
measurements  than  those  of  the  latter  substance.  Further,  there  is  a 
well-marked  difference  in  habit.  Crystals  of  the  dibromo-anhydride 
are  always  tabular,  whilst  those  of  the  chlorobromo-derivative  are 
much  more  prismatic  in  habit ;  this  is  mainly  due  to  a  large  develop- 
ment of  the  forms  p{110}  and  5(010}  on  the  latter  crystals. 

^The  behaviour  of  the  two  substances  after  melting  and  solidification 
is,  in  accordance  with  the  isomorphism,  extremely  similar." 


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138     KIPPING:  D£BIVATIVK8  OJT  CAMPHORIC  ACID.     PAKT  UL 


v-BronuHv-Maroeampharic  Acid,  C^lB.i2^rCl{(X)OR)^ 

This  acid  can  be  prepared  from  its  anhydride  by  the  same  method 
as  that  employed  in  the  case  of  the  dibromo-anhydride,  namely,  by 
dissolving  the  anhydride  in  concentrated  nitric  acid  (sp.  gr.  1*4),  and 
then  evaporating  the  solution  on  the  water-bath.  The  colourless 
crystals  of  the  acid  are  dried  on  porous  earthenware,  washed  with  a 
little  chloroform  to  remove  traces  of  unchanged  anhydride  which  may 
be  present,  and  then  dried  at  100^;  for  the  analysis,  a  sample  was  re- 
crystallised  from  ether,  as  the  crystals  retain  small  quantities  of 
occluded  nitric  acid,  which  is  not  easily  expelled  even  at  100^. 

01689  gave  0*2395  CO,  and  0*0693  H^O.  0  »  38*67 ;  H  -  4  56. 
CioH^^BrOlO^  requires  0* 3829  ;  H  =  4*46  per  cent. 

ir-BromoH(^-chlorocamphoric  acid  is  a  microcrystalline,  colourless 
powder,  as  prepared  in  the  above  manner ;  it  melts  at  about  197^  when 
heated  fairly  slowly  from  about  80^,  effervescing  vigorously,  but  as 
this  temperature  is  a  decomposition  rather  than  a  melting  point,  it 
varies  a  little  with  the  rapidity  of  heating.  There  is,  however,  a  much 
larger  difference  between  the  melting  points  of  the  bromochloro-  and 
dibromo-acids,  than  between  those  of  the  corresponding  anhydrides. 
In  all  ordinary  properties,  the  bromochloro-acid  resembles  the  dibromo- 
compound ;  it  is,  however,  rather  more  soluble  in  boiling  water,  from 
which  it  separates  in  long,  transparent  prisms,  which  seem  to  contain 
water  of  crystallisation,  as  they  become  opaque  when  heated  and  melt 
at  about  197°.  It  separates  from  cold  concentrated  nitric  acid  in 
nodular,  opaque  masses,  and  from  ethereal  chloroform  in  colourless, 
transparent,  well-defined  microscopic  prisms ;  its  behaviour  towards 
boiling  water  is  referred  to  later. 

v-Bromoeamphanic  Add,  CXJOH-CgHi^Br^^Y . 

Various  method^  can  be  adopted  for  preparing  this  compound  from 
dibromocaitphoric  anhydride,  or  from  the  corresponding  acid,  some 
of  which  l^ve  already  been  mentioned.  It  may  be  obtained  in  large 
quantities  by  boiling  the  finely  divided  anhydride  with  a  large 
volume  of  water,  but  as  this  process  occupies  a  long  time,  owing  to 
the  slight  solubility  of  the  anhydride,  the  following  method  is  more 
convenient. 

The  anhydride  is  dissolved  in  a  small  quantity  of  boiling  acetic 
acid,  and  after  adding  a  little  water  until  a  turbidity  is  just  produced 
in  the  hot  solution,  the  latter  is  heated  on  a  sand-bath,  more  water 


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KIPPma:  DERIVATIVES  Ot  CAHPHO&IG  ACID.     PABT  III.     1 

being  added  from  time  to  time  as  the  anhydride  decomposes ;  daring 
this  prooess,  the  solution  almost  invariably  acquires  a  distinct  bright 
pink  colour^  which  slowly  changes  to  brown,  the  liquid  then  depositing 
traoee  of  some  tarry  matter,  doubtless  due  to  imparity  in  the  (crude) 
anhydride  used.  The  hot  solution  is  finally  filtered,  and  on  cooling 
the  T-bromocamphanic  add  is  deposited  in  almost  colourless  needles ; 
further  quantities  are  obtained  on  evaporating  the  mother  liquors,  the 
yield  being  practically  theoreticaL 

For  analysis,  a  sample  was  purified  by  recrystallisation  from  a 
mixture  of  ethylic  acetate  and  chloroform  and  dried  at  100^. 

01676 gave 0-2518002 and 00697 H,0.    C -43-57;  H  =  4-91. 
OioHijBrO^  requires  C  =  43-32  ;  H  =  4-69  per  cent. 

v-Bromocamphanic  acid  usually  separates  from  hot  water,  in  which 
it  is  only  moderately  easily  soluble,  in  small,  well-defined,  lustrous 
prismSy  which  do  not  lose  in  weight  at  100^.  It  is  comparatively 
sparingly  soluble  in  boiling  benzene,  and  only  moderately  so  in  boiling 
chloroform,  but  it  dissolves  readily  in  acetic  acid,  alcohol,  and  ethylic 
acetate ;  it  crystallises  best  from  cold,  dilute  acetic  acid,  from  which 
it  iA  deposited  in  transparent  prisms  described  later.  It  melts  at 
176  ^tI27^  without  decomposing,  but  when  heated  at  its  boiling  point  it 
darkens  considerably  and  seems  to  give  off  a  little  hydrogen  bromide  ; 
the  distillate  soon  crystallises  on  cooling,  and  consists  of  slightly  im- 
pure bromocamphanic  acid. 

v^Bromocamphanic  acid  is  a  very  stable  substance  in  many  respects, 
and  boiling  nitric  acid,  dilute  or  concentrated,  does  not  oxidise  any 
appreciable  quantity  of  it  in  the  course  of  a  few  hours.  Prolonged 
b(^ing  with  a  solution  of  chromic  anhydride  and  dilute  solphuric 
acid  seems  to  result  simply  in  the  elimination  of  hydrogen  bromide, 
the  bromocamphanio  acid  being  converted  into  hydroxy-ci^-Tr-camphanic 
acid ;  the  last-named  compound  is  also  formed  when  the  bromo-acid  is 
boiled  with  an  aqueous  solution  of  silver  nitrate,  but  other  substances 
are  also  produced.  When  the  acid  is  treated  with  ammonia  under 
suitable  conditions,  a  product  is  obtained  which  is  almost  insoluble  in 
water,  but  which  has  not  yet  been  analysed  or  examined. 

Mr.  Pope's  description  of  this  substance  is  as  follows.  "  The  crystals 
of  bromocamphanic  acid  are  very  beautiful,  transparent,  orthorhombic 
prisms  (Fig.  3),  which  have  a  very  brilliant,  glassy  lustre.  The  prism 
|>{110}  is  always  dominant,  but  gives  poor  results  on  measurement 
owing  to  the  presence  of  vicinal  faces  and  of  striations  parallel  to  the 
c-axis;  the  forms  ^{011}  and  r{101}  are  next  in  size,  r{  101}  being 
usually  rather  the  larger,  and  give  very  brilliant  reflections,  so  that 
the  mMHrarements  obtained  from  them  may  be  relied  upon.  The 
piBaooid  c{001}  is  very  «mall  and  frequently  absent. 


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140      KIPPXNQ  :  DEBIVATIVES  OF  CAMPHORIC  ACID.     PART  iH. 

Fio.  8. 


"  Crjstallme  System. — Orthorhombic. 

a:  5  :c»l-4654: 1:0-9501. 
"Forms  observed.— c{001},  />{110},  ^{011},  r{lOl}. 
**  The  following  angular  measurements  were  obtained. 


Number  of 

Angle. 

measare- 
ments. 

limits. 

Mean. 

Calculated. 

cr=001:101 

9 

86n7'—  86'69' 

85*41' 

85'89'80' 

rr*  101:101 

29 

71  12—  71  26 

7119 

.^ 

rr= 101:101 

25 

108  84—108  48 

108  40 

108  41   8 

pq^UOiOll 

84 

70  41—  70  56 

70  49 

— 

^x=01l!l01 

29 

55  49—  56  16 

56  59 

56  57 

»y=101:ll0 

81 

58   5—  58  24 

58  15 

53  14 

g5r=i011:0lT 

16 

86  52—  87  20 

87    4 

87    8 

qq=zQll:Oll 

14 

92  87—  98  11 

92  65 

92  52 

(jy=t001:011 

15 

46    1—  46  54 

46  21 

46  26 

13pa:110:ll0 

87 

110  47—11158 

11126 

11123 

|>p=110:110 

24 

68  20—  69  18 

68  47 

68  87 

"  The  plane  c(OOl)  is  the  optic  axial  plane,  and  an  optic  axis  emerges 
obliquely  through  each  face  of  the  form /?{ 110} ;  the  double  refraction 
is  strong  and  the  optic  axial  dispersion  slight.  After  melting,  the 
substance  solidi^es  readily,  and  is  thus  obtained  in  large  individual 
flakes,  which,  are  often  marked  by  strin  crossing  each  other  at  about 
60^,  and  cracked  across  their  loiTgest  dimension  on  cooling ;  the  flakes 
are  frequently  perpendicular  to  an  optically  negative  bisectrix  of  a 
large  axial  angle." 

Methylic  fr-Bromoeamphanate,  COOMe*OgHijBr^_;[Y. 

This  ethereal  salt  is  conveniently  prepared  by  passing  hydrogen 
chloride  into  a  solution  of  the  acid  in  methylic  alcohol  and  then 

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KIPPINQ:   DEBIYATIYBS  OF  CAMPnORIC  ACID.      PART  III.      141 

evaporating  at  the  ordinary  temperatare ;  the  product,  which  is  slowly 
deposited  in  felted  needles,  can  be  purified  by  recrystallisation.from  a 
mixture  of  ether  and  chloroform. 

01662  gave  02777  COj  and  00832  HaO.     C=-45-67  ;  H-6-56. 
CjiHisBrO^  requires  C  =»  45*36 ;  H  =  616  per  cent. 

Methylic  ir-bromooamphanate  crystallises  from  ether  and  from  most 
other  solvents  in  long,  transparent  needles  melting  at  87 — 88° ;  it  is 
very  readily  soluble  in  cold  chloroform,  methylic  alcohol,  and  boiling 
ether,  but  comparatively  sparingly  soluble  in  light  petroleum.  Massive 
crystals  are  easily  obtained  from  a  solution  in  a  mixture  of  ether  and 
ohlorolbrm,  and  a  specimen  of  the  compound  thus  obtained  was 
examined  by  Mr.  W.  J.  Pope,  whose  report  is  now  given. 

*'The  crystals  of  methylic  bromooamphanate  are  transparent  ortho- 
rhombic  plates  or  prisms,  possessing  a  high  lustre  (Fig.  4)  ;  the  habit 
of  the  crystals  varies  considerably,  those  of  prismatic  habit  are 
lengthened  in  the  direction  of  the  axis-a,  and  somewhat  flattened  in 
that  of  the  5-axis,  the  dominant  forms  being  a{100}  and  r{101} ;  the 
tabular  crystals  are  flattened  on  two  parallel  faces  of  the  form  r{101}. 
Yery  good  results  are  obtained  on  measuring  the  crystals. 

Fio.  4. 


"CJ^stalline  System. — Orthorhombic. 

a:6:<i=10977:l:0-656^. 
«  Forms  observed,— a{  100},  ft{010},  ^{110},  r{lbl}. 
''The  following  angular  measurements  were  obtained. 


Kamber  of 
1      nients. 

Limits. 

Mean. 

47''40' 
42  18 
59    8 
6142 
69  45 

Calculated. 

ap=100:110 
pfrsll0:010 
ar=100:101 
rri=  101:101 
|r=110:101 

18 
12 
24 
16 
7 

47*84'— 47'47' 
42  12—42  27 
59    0—59  28 
61  81  —61  60 
69  89  —69  52 

42*20' 

61  44 
69  47 

VOL.   LXXV. 


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142      KIPPING:  DERIVATIVES  OF  CAMPHORIC  ACID.      PART  111. 

'^  There  is  a  poor  oonchoidal  cleavage  parallel  to  5{010},  and  the  axi8-5 
is  the  acute  bisectrix ;  the  optic  axial  plane  is  c(001)y  and  the  double 
refraction  is  positive  in  sign,  and  strong.  The  optic  axial  angle  is 
fairly  large  and  the  optic  axial  dispersion  is  slight. 

*'  The  substance  solidifies  readily  after  melting  on  a  microscope  slide 
under  a  cover  slip,  giving  large,  individual  flakes  ;  most  of  these  are 
nearly  perpendicular  to  an  optically  negative  bisectrix  of  a  very  large 
optic  axial  angle,  and  these  are  full  of  symmetrically  arranged  egg- 
shaped  bubbles  and  of  intersecting  striations.  A  few  fragments  are. 
usually  to  be  observed  which  show  no  bubbles  or  strie ;  these  are 
nearly  perpendicular  to  the  optically  positive  bisectrix  of  a  fairly  large 
optic  axial  angle.  This  modification  is  doubtless  identical  with  the 
crystals  measured  above." 

Methylic  ir-bromocamphanate  is  slowly  attacked  by  concentrated 
aqueous  ammonia  at  ordinary  temperatures,  and  is  thereby  converted 
into  a  crystalline  substance,  which,  judging  by  its  melting  point  and 
other  ordinary  properties,  is  identical. with  the  «--bromocamphanamide 
produced  by  the  action  of  aqueous  ammonia  on  trtr-dibromocamphoric 
anhydride.    This  compound  may  now  be  described. 

vBramotO'camphomamidef  NHg'CO'CgHijBr^Y. 

When  finely  divided  iruvdibromocamphoric  anhydride  is  left  in 
contact  with  concentrated  aqueous  ammonia  at  ordinary  temperatures, 
it  slowly  changes  into  a  rather  more  bulky  mass  of  small  prisms,  but 
without  passing  into  solution  to  any  noticeable  extent ;  after  keeping 
the  mixture  for  about  two  days,  the  product  is  separated  by  filtration 
from  the  ammoniacal  solution,  which  contains  a  small  quantity  of  a 
readily  soluble,  crystalline,  ammonium  salt,  washed  with  cold  water, 
and  recrystallised  from  dilute  methylic  alcohol.  The  substance 
obtained  in  this  way  is  the  amide  of  1l^bromorU^'Camphanic  acid,  and 
an  analysis  of  it  gave  the  following  result. 

0-1678  gave  0*2671  COj,  and  0-0796  HgO.    0  =  43-41 ;  H  =  5-27. 
CjoHi^OgBrN  requires  C«43-47;  H  =  507  per  cent. 

The  nature  of  this  compound  is  further  established  by  the  fact 
already  mentioned,  namely,  that  it  is  formed  on  treating  methylic 
ir-bromocamphanate  with  aqueous  ammonia,  and  also  by  its  behaviour 
on  hydrolysis ;  when  boiled  for  a  short  time  with  concentrated  hydro- 
chloric acid,  it  is  converted  into  a  crystalline  acid,  which  melts  at 
176 — 177^,  and  has  all  the  properties  of  ir-bromocamphanic  acid. 

ir-Bromo-u^camphanamide  crystallises  from  most  solvents  in  lustrous, 
transparent  needles  or  prisms  melting  at  161 — 162^ ;  it  is  very  readily 


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KIPPING  :    DERIVATIVES  OP  CAMPHORIC  ACID.      PART   III.      143 

soluble  in  cold  chloroform,  acetone,  ethylic  acetate,  acetic  acid,  and 
most  other  solvents,  and  it  also  dissolves  freely  in  boiling  water,  bat 
it  is  insoluble,  or  nearly  so,  in  a  cold  dilute  solution  of  sodium  car- 
bonate. It  seems  to  be  dimorphous,  as  the  transparent  crystals 
deposited  from  dilute  methylic  alcohol  become  opaque  at  about  140^ 
when  slowly  heated,  and  do  so  at  even  lower  temperatures  when  the 
tube  containing  them  is  rubbed  gently. 

FamuUian  qfTr-Bromocamphanic  Acid  from  v-BronKhto-chlorocamphorie 
Anhf^dride. — It  was  stated  in  the  introduction  that  ir-bromo-fo-chloro- 
camphoric  anhydride  is  decomposed  by  boiling  water,  giving  hydrogen 
chloride,  and  an  acid  identical  with  the  ir-bromo-tiM^amphanic  acid, 
prepared  in  a  similar  manner  from  1rt(^^ibromocamphoric  anhydride ; 
this  statement  rests  on  the  following  experimental  evidence. 

When  bromochlorocamphoric  anhydride  is  boiled  for  some  hours 
with  diluted  acetic  acid,  and  the  filtered  solution  then  allowed  to  cool, 
a  substance  crystallising  in  colourless  prisms  is  deposited  ;  this  com- 
pound, after  having  been  purified,  melted  at  176 — 177^,  and  in  appear- 
ance and  other  properties  seemed  to  be  identical  with  ir-bromo- 
camphanic  acid.  The  great  similarity  between  dibromo-  and  bromo- 
chloro-camphoric  anhydrides,  however,  if  repeated  in  the  case  of  the 
bromo-  and  chloro-camphanic  acids,  might  render  the  distinction 
between  the  two  latter  a  matter  of  some  difficulty ;  for  this  reason,  it 
was  necessary  to  make  the  following  analysis,  the  results  of  which 
show  that  the  decomposition  product  of  the  bromochloro-anhydride  is 
really  a  v-bromocamphanic  acid. 

0-1672  gave  0-2621  00,  and  00679  H^O.    0  =  43-74  ;  H  =  4*80. 
OioHjjBrO^  requires  0  =  43-32  j  H  =  4-69  per  cent. 

ffydroocf/^is-W'Camphamc  Acid, 

It  has  been  shown  in  earlier  papers  that  ets-ir-camphanic  acid  is 
slowly  oxidised  by  potassium  permanganate  in  alkaline  solution,  being 
converted  into  a  hydroxy-c{»-7r-camphanic  acid,  which  is  the  lactone  of 
a  dihydroxycamphoric  acid;  this  hydroxy-acid  can  be  obtained  in 
various  ways  from  dibromocamphoric  anhydride  and  its  derivatives. 

When,  for  example,  dibromocamphoric  anhydride  is  boiled^or  some 
time  with  alcoholic  potash,  or  fused  with  potash  at  a  moderate 
temperature,  both  the  bromine  atoms  are  removed,  and  hydroxy-oM- 
ir-camphanic  acid  can  be  isolated  from  the  product  by  methods  which 
it  is  unnecessary  to  describe.  Again,  when  ir-bromocamphanic  acid  is 
heated  with  silver  nitrate  in  aqueous  solution,  silver  bromide  is 
rapidly  deposited,  and  an  acid  having  all  the  properties  of  hydroxy- 
ei9-s^<:amphanic  acid  can  be  obtained  from  the  solution. 

A  number  of  experiments  were  made  in  the  hope  of  isolating  a 

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144      KIPPING  AND  HTLL  :  a-KETOTETRAHTDRONAPHTHALENB. 

dihydroxjcamphoric  acid,  or  the  corresponding  dilactone;  for  this 
purpose,  the  dibromo-anhydride,  dibromo-acid,  and  ir-bromocamphanic 
acid,  were  separately  treated  with  aqueous  silver  nitrate  under  various 
conditions  ;  in  nearly  every  case  the  product  seemed  to  be  a  mixture 
of  two  or  three  organic  compounds,  and  it  was  not  easily  separable 
into  its  components  by  fractional  crystallisation  or  by  other  methods ; 
hydroxy-cM-^r-camphanic  acid  was  isolated  in  almost  every  instance, 
and  also  a  crystalline  substance,  which  from  its  melting  point  and 
other  properties  was  found  to  be  identical  with  the  y-lactone  of 
hydroxycamphotricarboxylic  acid.  Further,  in  several  experiments, 
small  quantities  of  an  oily  product  were  obtained ;  this  substance, 
when  purified,  was  only  sparingly  soluble  in  boiling  water  (the  other 
two  products  are  readily  soluble),  and  apparently  insoluble  in  cold 
dilute  sodium  carbonate  ;  it  was  vigorously  attacked  by  hot  concen- 
trated nitric  acid,  being  converted  into  the  y-lactoneof  camphotricarb- 
oxylio  acid.  These  observations  seem  to  show  the  existence  of  a 
dilactone  of  dihydroxycamphoric  acid  amongst  the  products  of  the 
action  of  silver  nitrate  on  the  bromo-  and  dibromo-compounds  in 
question. 

Hydroxy-ots-ir-camphanio  acid  is  prepared  far  more  easily  by  one  of 
these  methods  than  by  the  oxidation  of  ct«-ir-camphanio  acid,  and  its 
investigation,  as  well  as  that  of  some  of  the  other  compounds  related 
to  it,  is  being  continued  ;  the  crystals  of  this  acid,  obtained  from  an 
acetone  solution,  are  of  large  size  and  suitable  for  goniometrio 
examination. 

Univebsity  Gollbob, 
Nottingham. 


XVII. — a-Ketotetrahydronaphthalene. 

By  Fbedkbio  Stanley  Eifpino,  Ph.D.,  D.Sc.,  F.R.S.,  and  Alfbxd 

Hill. 

The  conversion  of  phenylpropionic  chloride  into  a-hydrindone  by  the 
action  of  aluminium  chloride  under  the  conditions  described  by  one  of 
us  in  a  previous  communication  (Kipping,  Trans.,  1894,  65,  680)  is 
an  example  of  intramolecular  condensation  by  which  an  open-  is- 
oonverted  into  a  closed-carbon  chain ;  the  reaction  also  provides  by 
far  the  most  convenient  method  yet  known  for  the  preparation  of 
a-hydrindone,  as,  with  due  care,  the  yield  is  invariably  very  good,  and 
phenylpropionic  chloride  itself  can  be  obtained  without  any  difficulty 
in  almost  unlimited  quantity ;  this  method  of  preparation  was,  there- 
fore, made  use  of  in  later  investigations  of  the  derivatives  of  a-hydrin- 
done (Kipping  and  Revis,  Trans.,  1897,  71,  238). 

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KIPPINO  AND  HILL  :  A-KMOT£TBAHtDEONAPHTHAL£N£.      146 

That  such  a  reaction  would  be  capable  of  more  general  application 
wa8|  of  course,  extremely  probable,  bat  until  quite  recently  no  oppor- 
tunity offered  itself  of  putting  this  view  to  the  test  of  experiment ; 
now,  however,  the  reaction  is  being  tried  with  various  substances, 
and  in  the  present  paper  some  of  the  first  results  of  this  work  are 
described. 

Taking  the  well-known  synthesis  of  a-naphthol  from  phenyl-^y- 
crotonic  acid  by  Fittig  and  Erdmann  as  an  indication  of  the  ease  with 
which  intramolecular  condensation  may  occur  in  the  case  of  a  benzene 
derivative  containing  a  suitable  unsaturated  side  chain,  it  seemed  very 
probable  that  a  similar  change  might  be  brought  about  in  the  case  of 
{^enylbutyric  acid,  if  the  chloride  of  this  acid  were  treated  with 
alaminium  chloride  in  a  suitable  manner ;  if  so,  the  analogy  between 
phenylpropionic  and  phenylbutyric  acid  would  be  complete,  the  one 
giving  a-hydrindone,  the  other  a-ketotetrahydronaphthalene. 

Phenylbatyrio  chloride.  a-Eetotetrahydronaphthalene. 

Experiments  showed  that  a-ketotetrahydronaphthalene  is,  in  fact, 
formed  bj  the  action  of  alaminium  chloride  on  phenylbutyric  chloride 
under  the  oonditions  described  below,  but,  so  far,  satisfactory  yields 
have  not  been  obtained,  owing  probably  to  the  readiness  with  which 
the  ketone,  when  once  formed,  undergoes  further  condensation  of  the 
ordinary  type ;  a  sufficient  quantity  of  this  substance,  however,  has 
been  obtained  to  enable  us  to  study  its  properties  in  some  measure, 
and  to  prepare  from  it  various  crystalline  derivatives. 

orKetotetrahydronaphthalene  is  isomeric  with,  and  closely  related 
to,  the  /3-keto-compound,  which  was  first  prepared  by  Bamberger  and 
Lodter  {Ber.y  1893,  26,  1833)  by  the  action  of  alkalis  on  '<  tetrahjdro- 
naphthylene  chlorhydrin"  (2  :^  3-chlorhydroxytetrahydronaphthalene), 
and  afterwards  examined  by  Bamberger  and  Yoss  {Ber.f  1894,  27, 
1547).  As^  far  as  can  be  judged,  the  two  compounds  resemble  one 
another  very  closely  in  properties,  and  both  show  the  ordinary  general 
reactions  of  ketones ;  the  semicarbazone,  oxime,  hydrazone,  and  para- 
bromhydraxone  of  the  a-keto-compound  are  described  in  this  paper, 
the  oxime  and  hydrazone  of  the  ^-ketone  having  been  previously 
prepared  by  Bamberger  and  Voss  {he.  cit,). 

That  the  substance  we  describe  as  a-ketotetrahydronaphthalene  really 
has  this  constitution  is  shown,  not  only  by  its  method  of  formation 
and  ketonic  properties,  but  also  by  the  fact  that  it  can  be  indirectly 
converted  into  a  base  which  seems  to  be  identical  with  oc-tetrahydro- 


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146      KIPPINQ  AND  HILL  :  a-KETOTETRAUYDBONAPHTfiALEMS. 

a-naphthylamine ;  this  base  was  first  obtained  by  Bamberger  and 
Bammann  {Ber.,  1889,  22,  951)  by  reducing  tetrahydro-1 : 6-naphthyl- 
enediamine  with  sodiom  and  amylic  alcohol,  and  then  eliminating  tiie 
amido-group  combined  with  the  unreduced  aromatic  nucleus. 

^2       ^        /\^0H, 


JCH,  \/\/^^ 

1 : 5-Tetrahy(lrooaphtbyl-         Tetraliydro-a  naphthyl-  a-Ketotetrahydro- 

enediamine.  amine.  naphthalene. 

The  conversion  of  a-ketotetrahydronaphthalene  into  this  base  was 
accomplished  by  first  preparing  the  oxime,  and  then  reducing  the 
latter  with  sodium  amalgam  in  acetic  acid  solution. 

The  study  of  this  interesting  ketone  is  being  continued. 

A  portion  of  the  expense  incurred  in  this  and  in  two  earlier  inves- 
tigations of  a  similar  kind  (Kipping,  Trans.,  1894,  65,  680;  Kipping 
and  Eevis,  Trans.,  1897,  71,  238)  has  been  met  by  a  grant  .kindly 
awarded  by  the  Oovernment  Grant  Oommittee  of  the  Royal  Society. 

Experimental. 

Prepa/ration  qf  PhenyUmtyrie  Add, — ^The  preparation  of  a  large 
quantity  of  phenylbutyric  acid  by  the  method  which  we  employed  is 
not  a  very  easy  task,  but  we  were  unable  to  find  any  process  which 
appeared  to  be  more  suitable,  recorded  in  the  literature. 

Starting  with  benzaldehyde,  anhydrous  sodium  succinate,  and  acetic 
anhydride,  we  first  prepared  the  mixture  of  phenyl-)9y-crotonic  and 
phenylparaconio  acids  under  the  conditions  laid  down  by  Jayne 
{Anruden,  1883,  216,  97),  but  instead  of  then  separating  these 
two  compounds  by  dissolving  out  the  phenyl-)3y-crotonic  acid  with 
carbon  bisulphide,  we  submitted  the  dried  mixture  directly  to  dry 
distillation  under  reduced  pressure  (about  30  mm.),  whereby,  as 
Jayne  has  already  shown  {loo.  eU.),  the  phenylparaconic  acid  is 
decomposed  into  phenyl-)3y-crotonic  acid  •  and  carbonic  anhydride,  a 
small  quantity  of  phenylbutyrolactone  being  also  formed  from  the 
phenyl-^y-crotonic  acid  by  an  intramolecular  change.  The  distillate, 
which  solidifies  on  cooling  to  a  brown,  pasty,  crystalline  mass,  was 
spread  on  porous  earthenware  to  separate  the  phenylbutyrolactone 
and  other  oily  impurities,  and  afterwards  recrystallised  from  hot 
carbon  bisulphide,  from  which  the  phenyl-jSy^rotonic  acid  was  deposited 
in  almost  colourless  needles ;  the  last  portions  of  this  acid  generally 
contain  a  little  benzoic  acid,  this  compound  being  always  present  in 
the  original  condensation   product   in  large  quantities ;   it  is  best 


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KlPPIKQ  AND  HILL  :  a-KETOTETRAHyDBONAPHTHALENB.      147 

removed  by  heating  the  mixture  on  a  water-bath,  the  residue  being 
again  crystallised  from  carbon  bisulphide. 

The  phenyl-^y-crotonic  acid  was  thus  obtained  in  colourless  needles 
melting  sharply  at  86^,  but  the  yield  was  always  very  poor,  owing  to 
the  formation  of  tarry  matter  in  the  original  condensation  process. 

For  the  conversion  of  this  unsaturated  compound  into  phenylbutyrio 
acid,  the  pure  acid  was  reduced  with  sodium  amalgam  in  alkaline 
solution,  and  after  precipitating  with  hydrochloric  acid  and  filtering, 
the  rest  of  the  product  was  extracted  with  ether,  and  the  whole 
purified  by  recrystallisation  from  this  solvent ;  the  acid  then  melted 
at  47 — 48°  as  stated  by  Jayne  {toe.  cit.).  We  did  not  experience  any 
difficulty  in  reducing  the  phenyl-)3y-crotQnic  acid  at  ordinary  tempera- 
tures, although,  according  to  Jayne,  prolonged  treatment  and  warming 
are  necessary. 

Phenylbutyric  chloride,  OgHg-CHj-OHj-OHj-COCl,  is  easily  prepared 
by  treating  the  dry,  powdered  acid  with  a  slight  excess  of  the  theoreti- 
cal quantity  of  phosphorus  pentachloride  at  ordinary  temperatures,  a 
vigorous  action  immediately  setting  in ;  instead  of  separating  the 
product  from  the  phosphorus  oxychloride  by  fractional  distillation 
under  reduced  pressure,  as  in  the  case  of  phenylpropionic  chloride 
(Trans.,  1894,  QQ,  484),  we  merely  heated  the  oil  on  a  water-bath  under 
diminished  pressure  until  the  oxychloride  had  volatilised,  using  the 
residual  phenylbutyric  chloride,  which  is  sufficiently  free  from  impurity, 
for  the  subsequent  experiments. 

Phenylbutyric  chloride,  as  thus  obtained,  is  a  yellowish,  mobile 
liquid,  having  a  slight,  but  not  very  unpleasant,  odour ;  when  poured 
into  water,  it  rapidly  solidifies  to  crystals,  which  are  only  very  slowly 
decomposed  by  cold  water,  and  which  do  not  immediately  dissolve  in 
a  cold  dilute  solution  of  sodium  carbonate. 

Action  of  Aluminium  Chloride  on  Fhenyllmtyric  Chloride. 

Experiments  were  made  in  order  to  ascertain  the  conditions  under 
which  the  conversion  of  phenylbutyric  chloride  into  a-ketotetrahydro- 
naphthalene  could  be  accomplished,  and  we  commenced  by  employing 
very  much  the  same  method  as  in  the  case  of  a-hydrindone,  the  acid 
chloride,  mixed  with  about  four  times  its  weight  of  light  petroleum 
(b.  p.  40 — 60°),  being  treated  with  its  own  weight  of  anhydrous  alu- 
minium chloride.  Under  these  conditions,  however,  only  a  very 
slight  reaction,  if  any,  occurred,  and  even  after  heating  on  the  water- 
bath  during  30 — 40  minutes,  the  phenylbutyric  chloride  was  found  to 
be  unchanged ;  on  employing  as  diluent  a  sample  of  light  petroleum 
boiling  at  60 — 80°,  the  reaction  was  almost  as  sluggish  as  before,  but 
with  petroleum  boiling  at  100 — 110°  a  vigorous  evolution  of  hydrogen 


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14A     KIPPINQ  ANt>  diLt :  a-&EtOT£T^MYl>R0KAl»HTHAtEN& 

chloride  set  in  on  heating,  and  in  a  short  time  the  reaction  abruptly 
ceased.  An  examination  of  the  product  from  this  last  experiment 
showed  that  the  yield  of  ketone  was  extremely  small,  most  of  the  add 
chloride  having  been  converted  into  a  pale  brown  resin.  For  this 
reason,  a  smaller  proportion  of  aluminium  chloride  was  employed  in 
the  later  experiments,  and  the  results  appeared  to  be  distinctly  better. 

The  most  satisfactory  yield,  so  far,  has  been  obtained  by  working 
in  the  following  manner.  Fhenylbutyric  chloride  (5  parts)  is  dissolved 
in  light  petroleum  (26  parts)  boiling  at  100 — 110°,  aluminium  chloride 
(4  parts)  is  added,  and  the  mixture  is  rapidly  heated  on  a  boiling  water 
bath  in  a  flask  provided  with  reflux  condenser ;  after  a  very  short 
time,  hydrogen  chloride  is  very  rapidly  evolved,  and  during  this 
reaction  the  flask  is  repeatedly  and  vigorously  shaken.  At  the  end  of 
about  10  minutes,  or  when  the  evolution  of  gas  suddenly  ceases,  the 
contents  of  the  flask  are  cooled  and  water  carefully  added;  finally,  the 
mixture  is  submitted  to  distillation  in  steam.  The  petroleum  which 
passes  over  first  contains  only  a  small  quantity  of  the  ketone,  the  rest 
distilling  over  slowly  with  the  steam  and  leaving  in  the  flask  a  brown, 
oily,  non-volatile  substance,  which,  on  cooUng,  solidifies  to  a  brittle 
resin;  the  ketone  is  isolated  by  evaporating  the  petroleum  and  by 
extracting  the  aqueous  portion  of  the  distillate  with  ether. 

The  a-ketotetrahydronaphthalene  obtained  in  this  way  as  a  pale 
yellow  oil  is  probably  slightly  impure,  and  is  further  treated  in  the 
manner  described  below ;  the  yield  is  by  no  means  satisfactory,  being 
at  the  most  only  about  10  per  cent,  of  the  theoretical,  but  it  is 
probable  that,  as  in  the  case  of  a-hydrindone,  further  experiments  will 
lead  to  the  discovery  of  some  slight  modification  of  the  process  which 
will  give  much  better  results. 

The  principal  product  of  the  reaction  is  the  brown,  brittle  resin, 
referred  to  above ;  this  substance  is  probably  formed  from  a-ketotetra- 
hydronaphthalene  by  a  condensation  process  similar  to  that  which 
occurs  in  the  case  of  '<  anhydrobishydrindone,"  or  by  the  further 
action  of  phenylbutyric  chloride  on  the  ketone  in  presence  of 
aluminium  chloride.  To  obtain  some  information  on  this  point,  some 
of  the  resinous  substance  was  oxidised  with  nitric  add,  and  it  was 
found  to  be  ultimately  converted  into  phthalic  acid;  this  fact  seems 
to  justify  the  above  assumptions,  and  to  indicate  that  if  this  secondary 
reaction  could  be  prevented  the  yield  of  the  ketone  would  be  as  good 
as  in  the  case  of  a-hydrindone. 

CH  'CH 
a-EeioMrahydr(maplUhalene,  OeH4<\^^i^ 

'When  working  with  small  quantities  of  a-ketotetrahydronaphthalene, 
the  best  method  of  purification  is  doubtless  the  following.    The  crude 


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KIPPINQ  AND  HILL :  a-KBTOTSTBAHTBEONAPHTHALEKB.      l49 

oil  ia  oonyerted  into  its  sparingly  soluble  semicarbazone  in  the  manner 
described  later,  and  after  recrjstallisation  it  is  heated  in  a  small 
WfirtE  flask  with  rather  more  moderately-concentrated  hydrochloric 
acid  than  is  required  to  combine  with  the  semicarbazide ;  the  semi- 
carbazone is  thus  decomposed  with  regeneration  of  the  ketone,  which 
can  be  distilled  off  in  a  current  of  steam  and  extracted  with  ether. 
The  addition  of  a  little  acetic  acid,  in  which  the  semicarbazone  is 
readily  soluble,  hastens  the  reaction.  In  this  operation,  there  is  no 
appreciable  charring  if  the  pure  semicarbazone  be  employed,  and  the 
deoompodtion  appears  to  be  normal,  as  expressed  by  the  following 
equation. 

a-Ketotetrahydronaphthalene  is  a  colourless,  mobile,  highly  refrac- 
tive liquid.  It  does  not  crystallise  when  kept  for  some  days  at 
ordinary  temperatures,  or  when  cooled  to  0°,  whereas  the  correspond- 
ing /3-ketone  solidifies  when  cooled,  and  melts  again  at  18^  (Bamberger 
and  Yoss,  loe.  eU.) ;  it  does  not  seem  probable  that  this  difference  in 
behaviour  is  due  to  the  presence  of  impurity  in  the  a-ketone,  as  the 
prooees  just  given  appears  to  be  a  very  satisfactory  method  of  purifi- 
cation. 

orKetotetrahydronaphthaleoe  is  specifically  heavier  than  water  at  15^, 
and  ifl  moderately  easily  volatile  in  steam.  It  has  only  a  faint  odour, 
recalling  that  of  camphor,  but  when  warmed  it  has  a  distinct  odour 
of  peppermint.  It  shows  many  of  the  ordinary  reactions  of  a  ketone, 
and  yields  crystalline  products  with  hydroxylamine,  phenylhydrazine, 
^ ;  it  does  not  appear  to  dissolve  in,  or  to  combine  with,  sodium 
hydrogen  sulphite  in  aqueous  solution,  although  the  )9-ketone  forms  a 
crystalline  additive  product  with  this  reagent. 

The  ketone  itself  was  not  analysed,  as  its  composition  is  established 
by  its  method  of  formation  and  properties,  and  by  the  analysis  of  the 
semicarbazone. 


a-EetaMrahpdronaphthaJene  Semtcarbcuane,  CiqHjqIN*NH*C0*KH2. 

When  the  crude  ketone,  obtained  by  the  method  described  above, 
is  heated  with  semicarbazide  hydrochloride  and  sodium  aceta^  in 
aqueous  alcoholic  solution,  the  separation  of  an  almost  colourless, 
crystalline  compound  soon  commences,  and  the  reaction  is  completed 
by  warming  on  the  water-bath  during  about  2  hours;  the  hot 
solution  is  then  diluted  with  water,  allowed  to  cool,  and  the  product 
separated  by  filtration,  and  washed  well  with  cold  water. 

When  purified  by  recrystallisation  from  hot  alcohol  and  dried  over 
sulphuric  acid,  it  gave  the  following  result. 


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150     KIPPINQ  AND  HILL  :  a-KETOTETBAHTDHOKAPHTHALEN£. 

0-1640  gave  03885  00^  and  00968  HjO.    C  =  646 ;  H  =  66. 
OjiHigNgO  requires  0  «  65'0 ;  H  =  6*4  per  cent. 

a-Ketotetrahydronaphthalene  semicarbazone  crystallises  from  alcohol 
in  long,  transparent  needles  or  prisms,  usually  forming  aggregates  of  a 
rosette-like  form ;  these  crystals  are  distinctly  yellow,  their  colour  being 
almost  as  intense  as  that  of  quinone,  but  when  in  a  fine  state  of  division 
the  substance  appears  almost  colourless.  The  melting  point  is  not  very 
definite,  for  when  heated  moderately  quickly  the  finely-divided  sub- 
stance melts  at  about  217?,  but  larger  crystals  only  sinter  at  this 
temperature,  and  do  not  liquefy  completely  until  about  220%  when 
effervescence  sets  in  and  the  substance  darkens  slightly  ;  on  heating 
more  strongly,  a  large  quantity  of  gas  is  disengaged  and  a  yellow  liquid 
remains. 

The  semicarbazone  is  comparatively  sparingly  soluble  in  boiling 
chloroform  and  ethyUc  acetate,  and  apparently  insoluble  in  water ;  it 
dissolves  fairly  easily  in  boiling  alcohol  and  boiling  acetone,  and  also 
in  warm  acetic  acid,  but  it  seems  to  be  decomposed  on  boiling  its 
acetic  acid  solution.  A.s  stated  above,  this  compound  may  be  con- 
veniently employed  in  the  purification  of  the  ketone,  as  the  latter  ia 
immediately  regenerated  on  warming  the  semicarbazone  with  hydro- 
chloric acid ;  it  also  affords  the  best  means  of  detecting  and  identifying 
the  ketone,  the  phenylhydrazone  being  far  less  suitable  for  such 
purposes. 


a-Ketotetrahydranaphthalene  Phenylhydrazone,  CiQHjoIN'NHPh. 

This  compound  is  easily  obtained  by  treating  the  purified  ketone 
with  phenylhydrazine  acetate  in  dilute  acetic  acid  solution  in  the 
usual  manner,  combination  taking  place  spontaneously ;  after  warm- 
ing gently,  water  is  added,  and  the  product,  which  is  precipitated  as 
a  thick,  yellow  oil,  is  washed  well  with  cold  water,  and  then  dissolved 
in  methylic  alcohol.  From  this  solution,  the  hydrazone  separates,  on 
spontaneous  evaporation,  in  a  crystalline  condition,  but  if  the  warm 
solution  be  rapidly  cooled,  the  compound  is  generally  deposited  as  an 
oiL  The  crystals  obtained  from  methylic  alcohol  and  other  solventa 
are  massive,  transparent,  almost  colourless  six-sided  and  rhomboidal 
plates  melting  at  84 — 85^,  at  the  same  time  effervescing  and  decom- 
posing; they  are  readily  soluble  in  most  of  the  ordinary  organic 
solvents,  and  dissolve  comparatively  easily  even  in  boiling  light  pet- 
roleum, separating  again,  on  cooling,  in  lustrous,  transparent  prisms. 

The  hydrazone  is  very  unstable,  and  soon  decomposes  on  exposure 
to  light  and  air ;  its  behaviour  towards  hydrochloric  acid  seems  to  be 
similar  to  that  of  the  parabromo-derivative  described  below. 

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KIPPING  AND  HILL:  a-KETOTETRAHTDRONAPHTHALENE.      151 


a'KeU>Utrdhydronaphihalene  Para^amophenylhf/drazone, 
C,oHio:N-NH-CeH,Br. 

The  preparation  of  this  substance  from  the  purified  ketone  and 
parabromophenylhydrazine  is  carried  out  exactly  as  described  in  the 
case  of  the  preceding  componndi  interaction  taking  place  very  readily ; 
the  almost  colourless,  oily  product,  which  is  precipitated  on  the  addi- 
tion of  water,  crystallises  immediately  when  treated  with  a  little 
methylic  alcohol,  and  is  easily  purified  with  the  aid  of  this  solvent, 
from  which  it  separates,  on  cooling,  in  long,  colourless  prisms,  or  in 
massive,  transparent  crystals. 

It  melts  ^t  117 — 118^,  when  heated  fairly  quickly  from  about 
110%  effervescing  and  decomposing,  and  it  is  readily  soluble  in  cold 
ether,  ethylic  acetate,  acetic  acid,  and  benzene ;  it  also  dissolves  in 
boiling  light  petroleum,  but,  on  cooling,  separates  again  almost  com- 
pletely in  nodular  aggregates  of  needles.  It  is  more  stable  than  the 
hydrazone,  and  does  not  change  colour  when  exposed  to  light  and  air 
during  several  days. 

Attempts  to  regenerate  the  ketone  by  distilling  the  parabrom- 
hydrazone  with  moderately  concentrated  hydrochloric  acid  were  not 
successful ;  under  these  conditions,  the  bromhydrazone  is  converted 
into  a  crystalline  compound,  which  is  probably  produced  by  a  change 
analogous  to  that  which  occurs  in  the  formation  of  "  benzyleneindol " 
from  the  phenylhydrazone  of  a-hydrindone  (compare  B!ausmann^  Ber,^ 
1889,  22»  2019 ;  Kipping,  Trans.,  1894,  65,  494). 


a-Ketoieirahydranaphihaleneoximet  C^qH^qINOH. 

On  gently  heating  a  solution  of  the  purified  ketone  in  dilute 
methylic  alcohol  with  hydroxylamine  hydrochloride  and  excess  of 
potash,,  the  separation  of  a  crystalline  compound  soon  commences,  if 
the  alcohol  be  sufficiently  dilute,  and  on  allowing  the  solution  to 
evaporate  on  the  water-bath,  most  of  the  product  is  deposited  in 
colourless  plates.  It  is  easily  purified  by  recrystallisation  from  dilute 
methylic  alcohol,  the  lustrous,  transparent,  well-defined  rhomboidal 
crystals  thus  obtained  generally  exceeding  10  mm.  in  diameter.  It 
melts  at  102*5 — 103*5°  without  decomposing,  and  is  very  readily 
soluble  in  cold  ether,  chloroform,  mothylic  alcohol,  and  most  other 
solvents  ;  it  also  dissolves  freely  in  cold  concentrated  potash,  but  it  is 
insoluble,  or  nearly  so,  in  water* 


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152      KIPPING  AND  HILL  :  a-KBTOT£TRAHYDRONAPHTHALENE. 


Conversion  qf  a-Ketotetrahydronaphthalene  into  Tetrahydro^- 
na^^UhylamiiM. 

Although  the  method  of  formation  of  the  ketone  descrihed  above 
and  the  analysis  of  its  semicarbazone  left  little  room  to  doubt  that 
it  had  the  constitution  assigned  to  it,  we  thought  it  would  be  inter- 
esting to  try  and  convert  it  into  one  of  the  tetrahydronaphthalene 
derivatives  of  known  constitution ;  for  this  purpose,  experiments  were 
made  with  the  object  of  converting  the  ozime  into  the  tetrahydro-a- 
naphthylamine  described  by  Bamberger  and  Bammann  {Ber,^  1889, 
22,  951). 

Attempts  to  reduce  the  ozime  with  sodium  and  moist  ether  were  not 
successful  j  even  after  employing  a  large  excess  of  sodium,  a  portion 
of  the  ethereal  solution  gave,  on  evaporation,  crystals  of  the  un- 
changed oxime,  and  a  basic  substance  appeared  not  to  have  been 
formed  ;  we,  therefore,  tried  the  action  of  sodium  amalgam  in  warm 
dilute  acetic  acid  solution,  and  found  that  reduction  took  place  very 
readily.  After  using  the  amalgam  in  considerable  excess  of  the 
theoretical  quantity,  the  acid  solution  was  submitted  to  distillation 
with  steam,  but  as  no  unchanged  oxime  passed  over,  the  solution  was 
rendered  strongly  alkaline  with  potash,  and  again  submitted  to  steam 
distillation.  A  colourless,  strongly  basic  oil,  which  was  only 
moderately  soluble  in  water,  then  collected  in  the  receiver.  This 
aqueous  distillate,  having  been  mixed  with  excess  of  hydrochloric  acid 
and  evaporated  almost  to  dryness  on  the  water-bath,  left  a  consider- 
able quantity  of  a  salt  which  crystallised  in  needles  or  prisms,  and 
was  very  readily  soluble  in  water ;  the  yield  seemed  to  be  practically 
theoretical. 

In  order  to  prove  that  this  salt  was  the  hydrochloride  of  tetra- 
hydro-a-naphthylamine,  a  portion  of  it  was  roughly  dried  at  100^, 
and  then  heated  for  a  few  minutes  with  excess  of  acetic  anhydride ; 
on  subsequently  cooling  and  adding  water,  the  acetyl  derivative  of  the 
base  separated  in  colourless  needles. 

Bamberger  and  Bammann  {loc,  dt,)  describe  this  acetyl  derivative 
as  crystallising  from  very  dilute  alcohol  in  felted  masses  of  needles, 
and  they  give  148 — 149^  as  its  melting  point.  The  compound  we 
obtained  had  these  and  all  other  properties  mentioned  by  Bamberger 
and  Bammann,  except  that  it  melted  at  144 — 145%  and  its  melting 
point  underwent  no  change  on  recrystallisation.  As,  therefore,  there 
was  this  considerable  difference  in  melting  point,  which  is  difficult  to 
account  for,  further  evidence  as  to  the  identity  of  our  base  was 
desirable. 

For  this  reason,  we  prepared  the  jp^o^inoeMorufo,  a  salt  which  is 


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P(7RDIE  &  PITKEATHLY:  PRODUCTION  OP  ACTIVE  ACIDS,  ETC.       153 

immediately  precipitated  in  yellow  plates  or  prisms  on  the  addition  of 
platinic  chloride  to  a  solution  of  the  hydrochloride  of  the  hase.  This 
Gomponnd  crystallised  from  water  in  long,  flat,  orange-yellow  prisms, 
was  readily  soluhle  in  hot  water  and  cold  methylio  alcohol,  and  melted 
immediately  at  140°  when  suddenly  heated,  thus  indicating  that  it 
contained  water  of  crystallisation ;  these  properties  agreed  with  those 
assigned  to  the  platinochloride  of  tetrahydro-a-naphthylamine  hy 
Bamberger  and  Bammann,  and  our  salt,  like  theirs,  melted  at  190°, 
decomposing  and  effervescing;  the  temperature  at  which  the  salt 
melts  and  decomposes  varies,  however,  within  very  wide  limits, 
according  to  the  rate  of  heating,  and  on  heating  quickly  the  tempera- 
ture can  be  raised  to  about  197°  before  liquefaction  and  decomposition 
ensue. 

An  analysis  was,  therefore,  necessary  to  confirm  the  supposed 
identity  of  the  two  compounds. 

0*4543  salt,  dried  over  sulphuric  acid,  lost  0*0232  at  100°.  HgO  -=  51 . 

0*4311  anhydrous  salt  gave  0*1224  platinum.    Pt »  28*4. 

Calculated  for  (CioHi3N)2,H2PtCIe  +  2HjO,  H20  =  4-87  per  cent. 

Calculated  for  (CioHi3N)2,HjPtCle,  Pt  =  27*6  per  cent. 

On  ignition,  the  salt  gave  off  fumes  having  a  strong  odour  of 
naphthalene. 

Univkbsitt  College, 
nottikgham. 


XVIII. — Production  of  Optically  Active  Mono-  and 
Di-alhyloocysuccinic  Adds  from  Malic  and  Tartaric 
Acids. 

By  Thomas  Pubdie,  F.R.S.,  and  William  Pitkeathly,  B.Sc., 
Berry  Scholar  in  Science. 

It  has  been  shown  in  previous  papers  (Trans.,  1898,  73,  287,  862) 
that  the  high  optical  activity  of  the  ethereal  malates  and  lactates, 
prepared  from  (lie  respective  silver  salts,  is  due  to  the  production  of 
small  quantities  of  the  more  active  alkylozy-derivatives,  and  Bodger 
aQd  Brame  (Trans.,  1898,  73,  306)  were  consequently  inclined  to 
attribute  the  abnormally  high  rotation  of  the  ethereal  tartrates, 
which  they  prepared  from  silver  tartrate,  to  a  similar  cause.  On 
hydrolysing  specimens  of  methylic  tartrate,  on  the  other  hand,  which 
had  been  prepared  by  this  and  by  the  commoner  methods,  they  found 
that  the  products  diowed  practically  the  same  rotation,  which  sug- 

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154      PURDIE  AND  PITKEATHLY:  PRODUCTION   OF  OPTICALLY 

gested  the  possibility  that  the  ethereal  salts  from  the  two  different 
sources  might  be  isomeric. 

The  object  of  the  present  research  was  to  obtain  further  evidence 
of  the  production  of  alkylozy-derivatives  in  the  interaction  of  the 
silver  salts  of  hydrozy-acids  with  alkyl  iodides,  and  to  find  a  modifi- 
cation of  the  reaction  which  might  serve  as  a  practical  method  for  their 
preparation.  We  have,  accordingly,  made  further  experiments  on 
the  production  of  alkyloxysuccinates  from  silver  malate,  and,  Mr. 
Brame  having  kindly  left  us  to  continue  his  work,  we  have  examined 
the  product  of  the  action  of  isopropylic  iodide  on  silver  tartrate  for 
di-isopropoxysuccinic  acid.  We  find  that  this  compound  is  actually 
produced,  and  conclude,  therefore,  that  a  similar  reaction  oocurs, 
although  probably  to  a  smaller  extent,  when  other  alkyl  iodides  are 
used.  We  find  further  that  the  ethereal  malates  and  tartrates  can  be 
readily  alkylated  by  means  of  alkyl  iodide  in  the  presence  of  silver 
.oxide,  the  reaction  furnishing  a  convenient  method  of  preparing  the 
optically  active  mono-  and  di-alkyloxysuccinio  acids  from  malic  and 
tartaric  acid  respectively.  The  ethereal  di-alkyloxysuccinates  are 
highly  active  compounds,  and  their  presence  even  in  small  quantity 
would  account  for  the  abnormally  high  rotation  of  the  ethereal 
tartrates  prepared  from  silver  tartrate.  Observations  made  on  the 
metallic  salts  of  diethoxysuccinic  acid  also  explain  the  apparently 
anomalous  results  obtained  by  Bodger  and  Brame  in  the  hydrolysis  of 
methylic  tartrate. 


Action  of  Alkyl  Iodides  on  Silver  Malate, 

In  former  experiments  with  ethylic  iodide  {loe.  eit.)f  the  crude 
distilled  product  of  the  reaction  had  always  nearly  the  same  rotation, 
-U°  (^=1).  We  now  find  that,  by  modifying  the  conditions,  a 
somewhat  more  active  liquid  is  obtained,  although  in  no  case  is  the 
proportion  of  ethoxysuccinate  produced  large  enough  to  admit  of  its 
being  separated  from  the  malate.  Thus,  by  adding  the  iodide  (3  mols.) 
gradually  to  the  silver  malate  (1  mol.),  the  treatment  being  otherwise 
the  same  as  before,  a  product  was  obtained  which,  without  fractional 
distillation,  gave  the  rotation  — 15-31°.  Even  when  2  mols.  of  iodide 
only  were  used  and  benzene  added  to  moderate  the  action,  con? 
ditions  which  should  be  unfavourable  to  the  hydroxyl  group  being 
attacked,  the  ethoxysuccinate  was  formed  as  before,  the  ethereal  salt 
obtained  showing  a  rotation  almost  identical  with  that  just  quoted. 

In  attempting  to  prepare  isobutylic  malate  by  the  silver  salt 
method  (Trans.,  1896,  69,  824),  the  product  was  found  to  consist 
mainly  of  free  acid,  which,  however,  was  not  further  examined  at  the 
time;  as  it  seemed  possible  that  this  result  might  be  due  to  the 

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ACTIVE  MONO-  AND  0I-ALKYLOXY SUCCINIC  ACIDS,  ETC.      155 

formation  of  isobutoxysuccinic  acid,  we  have  investigated  the  reaction 
more  closely.  The  method  employed  was  the  same  as  before,  but  the 
.free  organic  acid  was  removed  from  the  product  before  distillation 
by  allowing  it  to  stand  over  potassium  carbonate.  In  an  experiment 
in  which  92  grams  of  malate  were  added  gradually  to  167  grams  of 
iodide,  the  yield  of  ethereal  salt  amounted  to  only  6  grams,  and  in 
another  experiment,  in  which  the  order  of  mixture  was  reversed,  the 
yield  was  still  less.  The  free  organic  acid,  which  was  isolated  as  in  a 
previous  similar  case  (Trans.,  1898,  73,  299),  gave,  on  heating  with 
a  solution  of  barium  hydroxide,  a  large  quantity  of  barium  malate ; 
when  dried  at  160^,  it  was  found  to  contain  50*89  per  cent,  of  barium, 
the  calculated  number  being  50*93.  The  filtrate  from  this,  on 
evaporation,  left  a  less  granular  and  more  soluble  salt,  which  analysis 
showed  to  be  barium  isobutoxysucoinate  contaminated  with  some 
malate.  Great  difficulty  was  experienced  in  freeing  the  isobutoxy- 
suocinic  add  from  malic  acid.  We  found,  finally,  that  although  both 
barium  salts  are  precipitated  on  boiling  their  aqueous  solutions,  the 
isobtttoxysnocinate  differs  from  the  malate  in  redissolving  readily 
when  the  solution  cools,  which  enabled  us  to  obtain  the  isobutoxy- 
suodnate  as  a  flocculent  powder  approximately  free  from  malate.  The 
results  of  the  combustion  of  the  substance,  dried  at  160^,  were  as 
follows. 

I.  C  =  28-93.    H  =  4*08  ;  Ba  =  42*71  per  cent. 
11.0  =  29*03.    H- 405 ;  Ba  =  42*36    „      „ 
CgH^OjBa  requires  0  =  29*64  ;  H  =  3*69  ;  Ba  =  4216  per  cent. 

In  very,  dilute  aqueous  solutions  (e  =  0*9132)  at  13°,  the  saH 
showed  the  specific  rotation  -21*4°.  The  silver  salt  could  not  be 
obtained  by  precipitation.  The  Imodium  salt,  prepared  from  the  barium 
salt,  gave  in  aqueous  solution  the  specific  rotation  -  27*8°  (e=  1*888), 
and,  on  analysis,  was  found  to  contain  19*46  per  cent,  of  sodium,  instead 
qf  the  calculated  number,  19*66.  The  rotations  quoted  are  much 
higher  than  those  of  the  corresponding  nuilates,  and  are  such  as 
butoxysuocinates  might  be  expected  to  exhibit. 
.  The  5  grams  of  ethereal  salt,  mentioned  above,  contained  a  small 
proportion  of  isobutylic  isobatoxysuccinate.  This  was  evident  from 
its  high  observed  rotation,  -  16*28°  in  a  100  mm.  tube,  that  of  the 
oorresponcUng  malate  being  only  -  11*60°  {ZeU.  physikal.  Chem.,  1895), 
17,  249),  and  was  confirmed  by  the  detection  of  barium  isobutoxy- 
suodnate  in  the  product  of  hydrolysis.  The  quantity  of  substance 
was  too  small  to  admit  of  its  being  purified,  but  it  showed  a  specific 
rotation  nearly  the  same  as  that  quoted  above,  namely,  -  20*81°  at 
10°  for  cs^  1*638.  These  observations  show  that  the  reaction  between 
isobutylic  iodide  and  silver  malate  does  not  follow  the  normal  course, 

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156     PURDIE  AND  PITKEATHLY:  PRODUCTION  OF  OPTICALLY 

but  that  the  main  product  is  free  malic  acid,  produced  probably  by 
the  decomposition  of  the  iodide  into  isobutylene  and  haloid  acid,  and 
that  a  considerable  quantity  of  isobutoxysuccinio  acid  is  also  formed. 
Mr.  J.  0.  Irvine  was  good  enough  to  examine  for  us  the  action  of 
secondary  butylic  iodide  on  silver  malate,  in  the  hope  that  this  iodidci 
like  isopropylic  iodide,  would  yield  a  larger  proportion  of  the  alkyloxy- 
acid.  He  obtained  from  the  product  only  a  small  quantity  of  a  very 
soluble  barium  salt  of  wax-like  appearance  which,  although  it  could 
not  be  obtained  quite  pure,  was  evidently  a  barium  butoxysuccinate. 
On  combustion,  it  gave  results  approximating  to  the  calculated 
numbers,  and  its  specific  rotation  in  dilute  aqueous  solution,  -  20*97% 
was  practically  the  same  as  that  of  the  isobutoxysuccinate. 

Action  of  liopropylic  Iodide  on  Silver  Tartiraie, 

Isopropylic  iodide  was  used  in  this  experiment,  previous  results  having 
shown  that  it  is  more  prone  than  other  iodides  to  the  reaction  by  which 
the  alkyloxy-acid  is  produced.  Sixty-eeven  grams  of  silver  tartrate 
(1  mol.)  were  gradually  added  to  134  grams  of  the  iodide  (about  4  mols.) 
previously  diluted  with  an  equal  volume  of  benzene,  and  the  mixture  was 
treated  as  in  previous  similar  experiments.  After  distilling  off  the  bens- 
ene  and  unaltered  iodide,  and  shaking  the  residual  liquid  with  a  solution 
of  sodium  carbonate,  a  small  quantity  of  an  oily,  ethereal  salt  remained, 
which,  as  it  was  too  dark  coloured  for  polarimetrio  observation,  was 
diluted  with  an  equal  bulk  of  alcohol  and  then  examined  in  a  100  mm. 
tube.  The  observed  rotation,  about  +  26%  showed  that  the  substance 
was  far  more  active  than  any  of  the  ethereal  tartrates.  A  crude, 
syrupy  acid,  obtained  from  this  by  hydrolysis  with  potassium  hydroxide, 
acidifying  with  sulphuric  acid,  and  extracting  with  ether,  showed  the 
specific  rotation  +  29^  in  about  a  10  per  cent,  solution,  an  activity 
much  exceeding  that  of  tartaric  acid.  The  barium  and  magnesium  salts 
did  not  crystallise ;  the  calcium  salt  was  very  soluble  in  cold  water, 
but  was  precipitated  as  a  crystalline  powder  on  boiling  its  aqueous 
solution.  Estimations  of  calcium  in  the  salt,  dried  at  130%  gave  the 
results  14*77  and  14*82  per  cent.,  the  calculated  percentage  for 
calcium  di-isopropoxysuccinate  being  14*70. 

The  production  of  the  alkyloxy-compound  in  the  reactions,  which 
have  been  described  in  this  and  previous  papers,  appears  to  be  due  to 
some  of  the  ethereal  salt  of  the  hydroxy-acid,  which  is  formed  in  the 
first  instance,  reacting  further  with  alkyUc  iodide  and  unaltered  silver 
salt  with  the  formation  of  silver  iodide,  ethereal  salt  of  the  alkyloxy- 
acid,  and  free  hydroxy-add,  which  is  always  present  in  the  product. 
The  free  alkyloxy-acid  or  its  acid  alkyl  salt,  which  also  frequently 
results  from  the  reaction,  may  be  produced  from  the  normal  alkyl 

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ACTIVK  MONO-  AND  DI-ALKYLOXYSUCCINIC  ACIDS,  ETC.      157 

salt  by  water  accidentally  present,  or  by  a  reaction  such  as  the 
following,  in  the  case,  for  example,  of  silver  malate  and  ethylic  iodide, 
OH-  CgH3(C00Ag)j  +  2EtI  =  OEt-0jH5(0OOEt)*0OOH  +  2AgL 

Consideration  of  the  reaction  in  qnestion  suggested  that  the  alkyla- 
tion  would  probably  be  much  more  complete  if  the  ethereal  salt  of  the 
hydrozy-add  was  first  prepared  and  then  treated  with  alkyl  iodide  in 
the  presence  of  silver  oxide,  or  other  metallic  oxide  of  a  similar  nature. 
Ethylic  malate,  ethylic  iodide,  and  lead  oxide  gave  a  n^ative  result, 
but  the  product  obtained  by  heating  the  malate  and  iodide  with 
mercuric  oxide  yielded,  on  distillation  in  a  vacuum,  an  ethereal  salt 
much  more  active  than  the  original  malate,  the  rotation  having  risen 
from  -11-8°  to  —30*7°  (^"=1)-  A  mixture  of  ethylic  malate  and 
isopropylic  iodide  reacted  very  vigorously  with  silver  oxide,  and  gave 
an  ethereal  salt  showing  the  rotation  -  30*5°.  As  these  results  indi- 
cated that  the  expected  reaction  had  occurred,  the  action  of  ethylic 
iodide  on  ethylic  malate  and  on  ethylic  tartrate  in  presence  of  silver 
oxide  was  examined  in  detaiL 


Preparcttion  of  BthyUe   EihoxyiuccvnaU  from  Ethylic  Malate. 

The  materials  used  were  52  grams  of  ethylic  malate,  the  rotation 
of  which  was  a«  - 11-83°  (?=1,  <  =  6°),  86  grams  of  ethylic  iodide, 
and  64  grams  of  dry  silver  oxide,  these  proportions  being  chosen  on 
the  assumption  that  the  reaction  occurs  in  accordance  with  the 
equation  OH'C3H3(OOOEt)j  +  2EtI  +  Ag30=  OEt-02Hj(COOEt)2  + 
EtOH  +  2AgI.  The  mixture,  which  underwent  an  energetic  reaction 
on  being  gently  warmed,  was  afterwards  heated  for  some  time  on  a 
water-bath,  then  diluted  with  benzene,  filtered,*  and  distilled  under 
reduced  pressure,  when  it  yielded  43  grams  of  a  liquid  having  a 
nearly  constant  boiling  point,  and  showing  the  rotation— 41*21°  in  a 
100  mm.  tube  at  6°.  Assuming  that  the  liquid  consisted  of  only 
ethylic  ethoxysuccinate  and  malate,  the  rotation  indicated  the 
IHreeence  of  about  60  per  cent,  of  the  former  compound.  To  remove 
the  malate,  the  mixture  was  shaken  repeatedly  with  a  cold  10  per 
cent,  aqueous  solution  of  potassium  hydroxide  until  the  residual  oil 
was  reduced  to  about  one-half  its  original  weight.  The  oil,  after 
being  washed  with  water  and  dried  with  calcium  chloride,  was  found 
on  distillation  to  boil  at  the  same  temperature  as  ethylic  c?-ethoxysuc- 
cinate  formerly  prepared  (Trans.,  1895,  67,  972),  namely,  at  124° 
under  a  pressure  of  10  mm.,  and  its  analysis  gave  the  following 
results  agreeing  with  the  composition  of  that  substance. 

*  The  silyer  residues  from  these  and  the  succeeding  experiments  were  black  and 
their  composition  remains  to  be  examined. 

VOL.  LXXV.  M 

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168      PUEDIE  AND  PITEEATHLY :  PRODUCTION  OF  OPTICALLY 

Found :  I.  0«64'63  ;  H  =  8-68  per  cent, 
n.  0  =  64-79;  H  =  8U    „      „ 

Calculated  :  Oa66'06;  H»8*26  per  cent. 

A  determination  of  the  specific  rotation  of  the  liquid  at  6^  gave  the 
following  result:  o=  -66-85°,  l^l,  d  6^4^ « 1-0601,  hence  [aj^- 
"  64*14^.  The  specific  rotation  of  ethylic  c^thozysucoinate  from  the 
active  acid,  which  was  obtained  by  resolution  of  the  raoemoid  com- 
pound {loe.  eU.9  p.  979),  was  +66-48^.  The  somewhat  lower  rotation 
now  found  is  accounted  for  by  the  substance  being  contaminated 
with  some  ethylic  f umarate,  produced  probably  in  the  preparation  of 
the  ethylic  malate.  The  specific  rotation  of  an  aqueous  solution  of 
l-ethoxysuecime  cicid,  which  was  obtained  by  hydrolysing  the  ethylic 
salt,  acidifying  the  product  and  extracting  it  with  etiier,  was  found  to 
be  [u]d=  -31-14°  (c  =  80588,  <  =  7°),  a  number  about  3° lower  than 
that  previously  found,  the  discrepancy  here  being  greater  than  in  the 
case  of  the  ethylic  salts  owing  to  the  fumaric  acid  being  chiefly  con- 
tained in  the  crystallised  portion  of  the  acid  which  was  used  in  the 
determination.  For  further  comparison  of  the  acids  from  the  two 
sources,  observations  were  made  on  the  otcid  ammorUum  saU  which 
could  be  freed  by  crystallisation  from  f umarate.  A  determination  of 
the  specific  rotation  of  the  hydrated  salt  in  aqueous  solution  at  8°  gave 
the  foUowing  result:  a= -6-00°,  /=2,  c  =  10'0288,  hence  [a]©- 
—  29-91°.  The  value  formerly  found  for  similar  concentration  at  17° 
was  28*46°.  To  obtain  evidence  of  the  purity  of  the  compound,  a 
silver  salt  was  made  from  it,  and  analysed  with  the  following  result 

Found:  0  =  18-90;  H  =  2-27;  Ag-67'76  and  67-69  per  cent. 
OeHgOjAgj  requires  0«19-16  ;  H«2-13  ;  Ag  =  67-46  per  cent. 

The  yield  of  alkyloxysuccinic  acid  by  the  process  which  has  been 
described  would  probably  be  increased  by  employing  a  larger  propor- 
tion of  alkyl  iodide  and  silver  oxide,  in  order  to  allow  for  the  loss  which 
is  doubtless  entailed  by  their  partial  direct  interaction. 

Preparaiicn  of  Ethylic  di-Diethoxy succinate  from  Ethylic  Tartrate. 

Attempts  have  been  frequently  made  to  alkylate  the  alcoholic 
hydroxyl  groups  of  tartaric  acid,  but  without  success.  Perkin  (Trans., 
1867,  20,  166),  by  the  action  of  ethylic  iodide  on  ethylic  monosodio- 
tartrate,  obtained  an  oil  which  he  thought  was  probably  ethylic  mon- 
ethyltartrate,  but  the  later  researches  of  Lassar  Oohn  {Ber,^  1887, 20, 
2003),  Mulder  {Rec.  Trav.  Chim.,  1889,  8,  361)  and  Freundler  (BuU. 
Soc.  Chim.y  1894, 11,  308)  have  shown  that  neither  the  sodium  nor 
potassium  derivatives  of  ethylic  tartrate  react  in  the  usual  way  with 
alkyl  iodides.      The  ethylic  diethoxysuccinate  which  Michael  and 

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ACTIVE  MONO-  AND   DI-ALKYLOXYSUCCINIC  ACIDS,   ETC.      159 

Booher  {Ber.y  1896, 29,  1792)  found  to  be  one  of  the  products  of  the 
action  of  sodium  ethoxide  on  ethylic  dibromosuccinate  and  on  ethylic 
acetylenedicarboxylate,  was  shown  by  these  authors  to  be  the  unsym- 
metricai  compound. 

The  proportions  of  ethylic  iodide  and  silver  oxide  employed  in  our 
experiments  were  6  mols.  of  the  iodide  and  3  mols.  of  the  oxide  to 
1  mol.  of  the  tartrate,  that  is  to  say,  an  excess  of  one-half  over  the 
calculated  quantity,  assuming  the  reaction  to  proceed  in  the  sense 
indicated  in  the  case  of  ethylic  malate.  On  adding  the  oxide  to  the 
mixture  of  iodide  with  tartrate,  the  reaction  set  in  spontaneously, 
and  became  so  violent  that  it  had  to  be  moderated  by  cooling.  The 
liquid  product,  obtained  as  described  under  ethylic  ethoxysuccinate, 
was  about  equal  in  quantity  to  the  tartrate  employed,  its  boiling 
point  was  nearly  constant,  and  its  observed  rotation  varied  in  different 
preparations  from  +83*5^  to  +92*5^  in  a  100  mm.  tube.  As  the 
percentage  numbers  found,  on  analysis,  were  somewhat  lower  than 
those  calculated  for  ethylic  diethoxysuccinate,  and  as  it  proved 
impossible  to  purify  the  substance  either  by  fractional  distillation  or 
by  shaking  with  water,  which  we  expected  would  remove  unaltered 
ethylic  tartrate,  if  present,  we  had  to  resort  to  the  method  of  partial 
hydrolysis  by  shaking  with  a  10  per  cent,  aqueous  solution  of 
potassium  hydroxide.  The  process  entailed  a  considerable  loss  of 
material,  but  the  residual  oil,  on  redistillation  (b.  p.  149 — 151°  at 
15  mm.),  had  increased  in  rotation  to  4-97*5°,  and  on  analysis  gave 
results  in  agreement  with  the  calculated  numbers. 

Found  :  L  0  =  54-99  ;  H-8-71  per  cent. 
IL  0»  64-87;  H-8-67    „      „ 
Oalculated  for  CuH^jOg :   0  «  5496 ;  H  =»  840  per  cent. 

The  specific  rotation  of  the  liquid  at  18°  was  as  follows :  a  «  +  97-52°, 
/=1,  d  18°/4°«  1-0460,  hence  [a]D=  +93-23°.  The  ethereal  salt  of 
lower  activity,  which  was  removed  by  the  partial  hydrolysis,  gave  an 
uncrystallisable  acid,  which  we  intend  to  examine  further. 

d'DidhoxtfSueeinie  ctcid,  which  was  obtained  from  the  ethylic  salt  in 
the  same  manner  as  the  monethoxy-acid,  is  sparingly  soluble  in 
benzene,  readily  soluble  in  ether,  alcohol,  chloroform,  and  water, 
from  which  it  crystallises  in  long  prisms  melting  at  126 — 128°.  The 
results  of  the  analysis  of  the  substance,  dried  at  100°,  were  as  follows. 

Found :  I.  0  =  46-86  ;  H  =  704  per  cent. 
II.  0=46-81;  H  =  6-90    „       „ 
Oalculated  for  C^H^fi^ :  0  =  46-60 ;  H  =  6-80  per  cent. 

The  acid  showed  the  following  specific  rotations  in  aqueous  solu- 

M  2 


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160      PUEDIB  AND  PITKEATHLY  :  PRODUCTION  OF  ACIDS,  BTC. 

tions  at  20°:   a- +6-73,  c«10-U88,  Ul,  hence  [a]i»=« +66-31°; 
a-  +2-70°,  c-4-0596,  ^=1,  hence  [a]D=  +66-51° 

The  silver  salt  is  soluble  in  water,  and  does  not  decompose  much  on 
evaporating  the  solution.  An  estimation  of  silver  in  the  salt  gave 
the  result  51-01  percent.,  the  calculated  number  being  51-43.  The 
acid  potassium  and  acid  ammonvwn  salts  are  crystalline.  The  normal 
sodium  salty  in  aqueous  solution  at  17°  showed  the  specific  rotation 
+  41*11°  (cs  3*138)  j  the  residue  left  on  evaporating  the  solution, 
dried  at  120°,  was  found  to  contain  18-35  per  cent,  of  sodium  instead 
of  the  calculated  number^  18*40.  The  ealeium  salt  is  very  soluble,  and 
was  not  obtained  in  the  crystalline  state.  The  barium  salt,  which  is 
characteristic,  is  sparingly  soluble  in  cold  water,  and  crystallises 
readily  in  large,  glassy  prisms,  containing  apparently  4HsO,  which  is 
lost  at  120—130°.  Analysis  of  the  anhydrous  salt  gave  the  following 
results. 

Found:  Oe 27*78;  H»3-77;  Ba« 39*94  and  4012  per  cent. 
Oalouhited:  0-28-15;  H«3-52;  Ba-=40*18       „      „ 

An  aqueous  solution  of  the  salt  at  16°  had  the  specific  rotation 
+  26  25°  (c=  1*8092). 

Ethylic  (i-diethozysuccinate  is  also  obtained  by  the  direct  action 
of  ethylic  iodide  and  silver  oidde  on  tartaric  acid,  but  the  yield  is 
smaller  than  when  the  alkyl  tartrate  is  used  as  the  starting  point. 
From  17  grams  of  tartaric  acid  we  obtained  in  this  way  12  grams  of 
an  ethereal  oil  having  the  same  boiling  point,  and  the  same  observed 
rotation,  +  85°,  as  the  crude  ethylic  diethozysuccinate  prepared  from 
ethylic  tartrate. 

The  optical  effect  of  the  replacement  of  the  alcoholic  hydrogen  of 
tartaric  acid  by  alkyl  radicles  is  of  the  same  nature  as  that  which 
attends  a  similar  substitution  in  lactic  and  malic  acids ;  the  sign  of 
rotation,  defined  in  the  case  of  lactic  acid  as  that  of  its  salts,  remains 
unchanged  ;  a  striking  rise  of  activity,  observable  more  particularly 
in  the  free  acids  and  the  ethereal  salts,  is  produced,  and  the  specific 
rotation  of  the  acids  in  aqueous  solutions  of  varying  concentration 
becomes  more  constant.  Thus,  in  passing  from  tartaric  to  diethozy* 
succinic  acid  the  molecular  rotation  of  the  ethylic  salt  is  raised  from 
+ 15*8°  to  +  244-3°,  and  that  of  the  free  acid  at  similar  concentration 
from  +20*6°  to  +136*6°.  The  ionic  rotation,  however,  does  not  ez^ 
perience  a  proportional  rise,  the  result  being  that,  whilst  in  the  case 
of  the  three  hydrozy-acids  mentioned  the  molecular  rotations  of  the 
alkali  salts  in  dilute  solution  greatly  ezceed  those  of  the  free  acids, 
these  rotations  become  nearly  equal  in  the  case  of  the  alkylozypro^ 
pionic  compounds,  and  the  order  of  their  value  is  rever^  in  ^he  cetse 
of  the  mono-  and  di-alkylozysuccinic  compounds. 

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CROSSLET  Al^D  LB  SUEUR :  CONSTITUTION  OF  FATTY  ACIDS.      161 

Our  observations  furnish  a  satisfactory  explanation  of  the  apparently 
anomalous  results  obtained  by  Rodger  and  Brame,  which  have  been 
already  referred  to.  An  admixture  of  6  per  cent,  of  ethylic  cMi 
ethoxysQocinate  would  suffice  to  account  for  the  high  rotation  of  the 
ethylic  tartrate  which  they  prepared  by  the  silver  salt  method,  but 
the  difference  between  the  rotations  of  the  products  of  hydrolysis  of 
such  a  mixture  and  of  pure  ethylic  tartrate  respectively  would  not, 
under  the  conditions  of  the  experiment  described  by  them,  amount  to 
more  than  O'l— 0-2®. • 

The  action  of  alkyl  iodides  and  silver  oxide  on  the  alkyl  salts  of 
optically  active  hydroxy-acids  furnishes  a  general  method  of  obtaining 
the  active  alkyloxy-acids.  We  have  used  the  method  with  success  for 
the  preparation  of  alkyloxypropionic  and  alkyloxyphenylacetic  acids 
from  active  lactic  and  mandelic  acids,  and  we  are  at  present  studying 
the  application  of  the  alkylating  agent  to  the  alkyl  tartrates  in 
general  and  to  other  compounds. 

Ukitsd  Collbob  of  St.  Salvator  and  St.  Lbonard, 
Univbbsity  of  St.  Andrews. 


XIX. — Determination  of  the    Constitution  of  Fatty 

Acids.     Part  L 

By  Arthur  William  Cbosslby  and  Hsnrt  Bondbl  Lb  Sueur. 

Some  short  time  ago  one  of  us,  in  conjunction  with  Professor  Ferkin 
(Trana,  1898,  73,  1),  described  an  investigation  of  a  complicated 
mixture  of  fatty  acids  derived  from  the  fusion  of  camphoric  acid 
with  alkalis ;  as  the  difficulties  encountered  in  identifying  some  of 
the  fatty  acids  were  very  great,  it  was  considered  desirable  to  try 
and  devise  a  method  for  the  determination  of  the  constitution  of 
such  acids,  and  the  object  of  this  paper  is  to  give  a  short  account  of 
experiments  which  have  been  carried  out  in  this  direction. 

So  far  as  our  present  experiments  go,  we  think  they  may  be 
described  as  satisfactory,  and  although  the  method  may  not  be  an 
infallible  one,  it  seems  likely  to  prove  of  considerable  importance  as 
a  means  of  establishing  the  constitution  of  organic  acids. 

The  method  of  procedure  which  was  suggested  to  us  by  Professor 
Perkin  is  the  foUowing.  Starting  with  a  fatty  acid,  X*CK^*  CH,*  COOH, 
this  is  first  converted  into  the  ethylic  salt  of  the  monobromo-deriva- 
tive  by  Yolhard's  process  (^ntio/an,  1887,  242,  61) ;  from  the  work  of 

*  The  experiment  referred  to  was  made  on  the  methylic  tartrates,  bnt  this  wonld 
not  materially  alter  the  result  as  stated  above. 

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162      CBOSSLET  AND   LE  SUEUR  :  DETERKINA.TION   OF  THE 


Auwers  and  Bemhardi  {B$r,f  1891,  24,  2209)  and  others,  there  can 
be  no  doubt  that,  under  these  conditions,  the  bromine  atom  takes  up 
the  a-position,  yielding  the  substance  X- CH,*  ^^^^'^^^^^^^^*  ^^^* 
brom-ethereal  salt  is  then  treated  with  quinoline  or  diethylaniline 
(compare  Weinig,  Annalm^  1894,  280,  253),  whereby  the  elements 
of  hydrobromic  acid  are  removed,  and  the  ethylic  salt  of  an  unsatu- 
rated acid  of  the  acrylic  series,  X*OHIGH*COO£t,  is  produced.  The 
free  acid  obtained  from  this  salt  by  hydrolysis  is  then  oiddised,  first 
with  potassium  permanganate,  giving  rise  to  the  corresponding 
dihydroxyacid,  X-CH(OH)*CH(OH)-COOH,  and  then  with  chromic 
acid,  when  the  molecule  is  broken  down  at  the  position  occupied  by 
the  double  bond  in  the  unsaturated  acid,  giving  X*COOH  and 
COOH-COOH. 

The  result  is,  therefore,  the  production  of  oxalic  acid  and  a  fatty 
acid  (or  ketone)  containing  two  carbon  atoms  less  than  the  original 
acid,  and  as  the  number  of  isomerides  decreases  greatly  with  loss  of 
two  carbon  atoms,  the  possibility  of  identification  is  much  enhanced. 
We  have  carried  out  this  process  with  three  acids,  namely,  valeric, 
t9o-valeric,  and  wo-butylacetic  acids,  as  we  considered  that  the 
oxidation  products  of  the  acids  of  the  acrylic  series  corresponding 
with  these  fatty  acids  would  be  typical  examples  of  what  might  be 
expected  to  be  met  with  in  actual  determinations.  Thus  valeric  acid 
gives  ethylacrylic  acid,  and  this,  on  oxidation,  propionic  acid  {fwrmal 
acid)  ]  Mo-valeric  acid  gives  dimethylacrylic  acid,  which  then  yields 
acetone  (hUone) ;  and  wo-butylacetic  acid  gives  wo-propylacrylic  acid, 
and,  on  oxidation,  ifo-butyric  acid  (UfHioid), 

With  the  three  acids  mentioned,  the  method  works  well.  In  all 
cases  we  have  been  careful  to  note  the  yields  of  substances  obtained 
in  the  various  stages,  and  there  is  h^re  appended  a  tabulated  list  of 
results.  The  numbers  express  the  percentage  yields,  and  are  referred, 
in  the  case  of  the  unsaturated  ethereal  salt  and  acid,  to  the  amounts 
theoretically  obtainable  from  the  brom-ethereal  salt  employed ;  and 
in  the  case  of  the  "  acid  or  ketone  produced  on  oxidation,"  to  the 
amounts  theoretically  obtainable  from  the  unsaturated  acid  used. 


Acid  employed. 

Brom- 
ethereal 
salt 

Unsaturated 

ethereal 

aalt. 

Unsaturated 
acid. 

Acid  or  ketone 

produced  on 

oxidation. 

Valeric  acid 

97-5 
98^0 

62*0 
80-0 
70-0 

41-0 

66— (M) 

61*0 

68*0 

iso-Valeric  acid 

iso-Batylacetic  acid. 

47-0 
60-0 

The  poor  yield  of  unsaturated  ethereal  salt  obtained  from  ethylio 
bromovalerate  is  accounted  for  by  the  fact  that  thete  is  also  pro- 
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CONSTITUTION  OF  FATTY  ACIDS.      PART  I.  168 

ducod  a  coiisi4erabIe  quantity  of  some  substance  of  higher  boiling 
point,  which  is  at  present  under  investigation  ;  and  the  comparatively 
small  amount  of  the  solid  dimethylacrylic  acid  obtained  from  its 
ethylic  salt  is  due  to  the  fact  that  an  oily  substance  is  produced  at 
the  same  time  (see  page  164).  In  no  case  was  oxalic  acid  identified 
in  the  products  of  the  reaction,  nor  could  it  be  expected  to  resist  the 
action  of  the  strong  oxidising  agents  employed. 

We  have  experimented  with  both  quinoline  and  diethylaniline, 
using  them  as  reagents  for  the  elimination  of  the  elements  of  hydro- 
bromic  acid,  and  £nd  that,  with  the  lower  fatty  acids,  the  one  gives 
quite  as  good  results  as  the  other,  but  with  the  higher  fatty  acids 
diethylaniline  is  to  be  preferred.  For  example,  in  the  case  of  ethylic 
bromisobutylacetate,  the  42  per  cent,  yield  of  ethylic  isopropyl 
acrylate,  obtained  when  using  quinoline,  was  increased  to  70  per  cent. 
by  employing  diethylaniline.  Quinoline  always  gives  rise  to  tarry 
products,  which  are  not  easy  or  agreeable  to  work  with,  whereas 
diethylaniline  does  not ;  in  the  latter  case,  however,  the  substances 
require  to  be  heated  together  for  a  much  longer  time,  and  it  is  very 
difficult  to  eliminate  the  last  traces  of  hydrobromic  acid.  As,  how- 
ever, the  unsaturated  ethereal  salts  are  subsequently  heated  with 
alcoholic  potash,  the  latter  objection  is  of  no  great  moment. 

We  intend  to  further  test  the  efficacy  of  the  method  by  trying  it  on 
other  acids,  such  as  (a)  stearic  acid,  and  from  preliminary  experi- 
ments already  made  with  this  acid,  it  seems  highly  probable  that  the 
various  reactions  will  take  place  as  expected.  The  insolubility  of  the 
hydroxylated  higher  fatty  acids  in  water  may  render  the  oxidation 
with  chromic  acid  a  difficult  operation,  in  which  case  it  will  be  of 
interest  to  see  whether  fusion  with  potash  will  serve  a  similar  purpose. 

(b)  It  will  be  noticed  that,  among  the  acids  examined,  none  contain 
BXkyl  groups  in  the  a-position.  In  such  a  case,  as,  for  example,  ethyl- 
isopropylacrylic  acid,  quite  a  new  point  is  raised.     This  acid, 

C2Hj.CH(C3H,).COOH, 
still  contains  one  a-hydrogen  atom,  and  should,  therefore,  yield  an 
a-brom-ethereal  salt  in  the  usual  manner;  but  when  the  latter  is 
trei^ted  with  quinoline,  there  are  two  possible  ways  in  which  hydro- 
bromic acid  may  be  eliminated  (compare  Perkin,  Trans.,  1896,  09, 
1466),  giving  rise  to 

(CH8)2CH-(:|-COOH  (CH3)2C:(p-  COOH 


CH3 


or 


Methyl-a-iaopropylacrylic  acid.  Dimethyl-a-ethylacrylic  acid. 

The  study  of  the  oxidation  products  of  the  unsaturated  acid  or 
acids  produced  would,  therefore,  be  of  special  importance. 

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164      CR088LEY  AND  LE  SUEUR  :  DETERMINATION  OF  THE 

(c)  The  method  may  also  prove  to  be  applicable  in  the  case  of  di- 
basic acids,  and  we  propose  to  try  it  on  pimelic  (isopropylsuccinic)  acid. 

Experimental. 

Acetone  from  Isovaleric  Acid. 

Instead  of  starting  with  isovaleric  acid,  the  ethylic  salt  of  a-brom- 
isovalerate  supplied  by  Kahlbaum  was  employed,yhich,  on  distillation, 
boiled  constantly  at  185 — 186^,  and  a  bromine  determination  gave 
the  following  numbers. 

0-2514  gave  02275  AgBr.     Br  =  38-50. 

C^HgBr-COOOgHg  requires  Br  =  38-28  per  cent. 

Treaiment  of  Ethylic  a-BromiaovcUerate  toith  QuinoUne, — Weinig  (An- 
nalen,  1894,280, 253)  has  shown  that  diethylaniline  may  be  used  instead 
of  alcoholic  potash  for  the  elimination  of  the  elements  of  hydrobromic 
acid,  and  later  Perkin  and  Goodwin  (this  Journal,  1896,  69,  1470) 
described  experiments  in  which  they  employed  quinoline  for  the 
preparation  of  dimethylacrylic  acid  from  ethylic  a-bromisovalerate. 
We  have  followed  their  instructions  exactly,  using  50  grams  (1  mol.) 
of  the  brom-ethereal  salt  and  70  grams  (2  mols.)  of  freshly  distilled 
coal-tar  quinoline  ;  on  fractionating  the  product,  it  was  found  to  distil 
between  153^  and  155^  as  a  colourless  oil  of  penetrating  odour. 
The  yield  is  80  per  cent,  of  the  theoretical. 

This  ethereal  salt  is  readily  saponified  by  alcoholic  potash,  and  the 
dimethylfiorylic  acid  formed  boils  constantly  at  a  temperature  of  114^ 
under  a  pressure  of  40  mm.  On  standing,  the  distillate  solidifies 
almost  completely  to  a  mass  of  needle-shaped  crystals,  which,  after 
being  freed  from  the  mother  liquor  by  spreading  on  a  porous  plate 
and  recrystallisation  from  light  petroleum  (b.  p.  60 — 80^),  melted  at 
68*5 — 69^,  and  gave  the  following  results  on  analysis. 

0-1047  gave  02296  CO,  and  0-0744  H,0.     C  =  5980  ;  H  =  7*90. 
CfiHgOg  requires  0=  60-00  ;  H«8-00  per  cent. 

The  yield  of  pure  acid  is  from  55 — 60  per  cent,  of  the  theoretical 
obtainable  from  the  brom-othereal  salt  employed.  On  extracting  the 
porous  plate  just  mentioned  with  ether,  a  small  amount  of  an  oily 
liquid  was  obtained  which  showed  no  signs  of  solidifying  even  after 
long  standing,  and  which  was  not  further  investigated. 

Perkin  and  Goodwin  {loc,  cit,)  also  mention  this  oily  bye-product. 

Treatment  of  Ethylic  a-Bromieovalerate  with  Diethylaniline. — In  using 
quinoline  for  the  elimination  of  the  elements  of  hydrobromic  acid, 
there  is  always  a  considerable  quantity  of  tarry  matter  formed,  and 
in  later  experiments  we  found  that  diethylaniline  could  be  used  with 

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CONSTITUTION  OF  FATTY  ACIDS.     PART  I.  166 

advantage  instead  of  quinoline;  the  yield  of  unsaturated  ethereal 
salt  is  considerably  increased,  and  no  tarry  products  are  produced, 
although  the  mixture  requires  to  be  heated  for  a  much  longer  period. 
The  yield  of  ethylic  dimethylacrylate  as  obtained  in  the  experiments 
just  described  is  good,  but  we  thought  it  of  sufBicient  interest  to  try 
the  effect  of  diethylaniline  on  ethylic  a-bromisovalerate.  The  process 
was  carried  out  exactly  as  described  on  page  166. 

There  is,  however,  in  this  case,  no  particular  advantage  to  be  de- 
rived, for  the  yield  of  ethylic  dimethylacrylate  is  no  higher  than  when 
quinoline  is  employed. 

Oxidation  qf  JHmethylacryUo  Acid  with  Potiunum  Permangcmate, — 
Ten  grams  of  dimethylacrylic  acid  were  neutralised  with  potassium 
hydroxide  and  dissolved  in  600  c.c.  of  water  ;  the  whole  was  stirred 
with  a  turbine,  and  maintained  at  0^  throughout  the  operation  ;  a  rapid 
current  of  carbonic  anhydride  was  then  passed  in,  and  a  cold  solution 
of  12  grams  of  potassium  permanganate  in  400  c.c.  of  water  gradually 
added  from  a  tap  funnel.  After  standing  overnight,  the  liquid  was 
filtered  from  precipitated  manganese  dioxide,  and  evaporated  to  a 
small  bulk;  no  attempt  was  made  to  isolate  the  dihydroxy-acid 
produced,  but  the  liquid  was  at  once  submitted  to  the  process  of  : — 

Oxidation  with  Potassium  Diehrovnate  and  Svlphwiic  Aeid. — For  this 
purpose,  the  evaporated  liquid  was  placed  in  a  flask  connected  with  a 
condenser,  and,  after  warming  to  70^  on  the  water-bath,  a  solution  of 
30  grams  of  potassium  dichromate  in  dilute  sulphuric  acid  was  slowly 
run  in,  the  heating  continued  for  eight  hours,  and  the  whole  steam 
distiUed.  The  distillate,  which  was  slightly  acid  to  litmus  paper,  was 
carefully  neutralised  with  potassium  hydroxide,  and  again  steam  dis- 
tilled ;  on  adding  an  alcoholic  solution  of  parabromophenylhydrazine 
to  the  distillate,  there  was  an  immediate  and  copious  precipitate, 
which  was  collected  and  dried  on  a  porous  plate.  After  recrystallisation 
from  light  petroleum  (b.  p.  80 — 100^),  it  was  obtained  as  beautiful, 
shining  scales  melting  at  94^  Bromine  determinations  gave  the 
f oUowing  results. 

L  0-2886  gave  0*2314  AgBr.    Br » 3409. 
II.  0-1226    „    0-0998  AgBr.     Br » 34*58. 

(OH3)sO:N*NH-O0H4Br  requires  Br  »  35*24  per  cent. 

Although  the  figures  obtained  are  not  so  good  as  might  be  desired, 
there  can  ^be  no  doubt  that  this  substance  is  the  parabromophenyl- 
hydrazine compound jof  acetone  (compare  Neufeld,  AnnaUn,  1888,  248, 
96),  the  ease  with  which  it  undergoes  decomposition  accounting  for 
the  lowness  of  bromine  found. 

The  parabromophenylhydrazine  compound  obtained  weighed  10*7 
grams,  whereas  the  amount  theoretically  obtainable  from  10  grtims  of 

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166       CROSSLET  AND   LE  SIT  EUR :  DETERMINATION  OF  THE 

dimethylacrylic  acid  is  22*7  grams  ;  this  is  a  47  per  cent,  yield  of  the 
substance. 

The  residue  from  the  steam  distillation  was  examined  for  oxalic 
acid,  after  removing  the  chromium  by  the  use  of  sulphurous  acid  and 
then  boiling  with  excess  of  sodium  carbonate.  No  traces  of  the  acid 
were  found,  nor  is  this  to  be  wondered  at,  as,  when  produced,  it  would 
at  once  be  further  oxidised  to  carbonic  anhydride  and  water,  in 
presence  of  the  strong  oxidising  agent  employed.  This  remark  also 
applies  to  the  other  oxidations  mentioned  in  this  paper ;  in  no  case 
was  any  oxalic  acid  detected. 

Propionic  Add  from  Valeric  Acid. 

Preparation  qf  Valeric  Acid, — This  acid  was  prepared  by  the  con- 
densation of  ethylic  sodiomalonate  and  normal  propylic  iodide,  and, 
after  saponification,  heating  the  propylmalonic  acid  so  formed.  It 
boiled  constantly  between  184°  and  185°  (uncorr.). 

Brominatian  qf  Valeric  Add, — Forty-four  grams  of  valeric  acid  were 
brominated  with  135  grams  of  dry  bromine  and  4*5  grams  of  amorphous 
phosphorus  in  the  usual  manner,  the  product  slowly  poured  into  three 
times  its  volume  of  absolute  alcohol,  and  the  ethylic  a-bromovalerate 
extracted  with  ether  and  distilled  under  diminished  pressure.  It 
boils  constantly  at  a  temperature  of  110°  (40  mm.),  and  is  obtained 
in  nearly  theoretical  amount  (97*5  per  cent.). 

I^reaiment  qf  Ethylic  a-Bromovalerate  tvith  DiethylanUine. — Seventy- 
six  grams  (1  mol.)  of  the  brom-ethereal  salt,  and  115  grams  (2 
mols.)  of  diethylaniline,  were  heated  in  two  portions  in  a  flask 
attached  to  an  air  condenser  and  containing  a  thermometer,  so  that 
the  temperature  of  reaction  could  be  noted ;  this  begins  at  about  175°, 
and  the  thermometer  rises  rapidly  to  190 — 200°  at  which  temperature 
the  whole  was  maintained  for  6  hours.  The  product,  when  cold, 
was  poured  into  excess  of  dilute  hydrochloric  acid,  and  extracted  with 
ether,  <bc.,  but  as  it  was  found  to  contain  bromine,  it  was  again  heated 
with  diethylaniline  (1  mol.)  for  16  hours  at  190—200°.  After  ex- 
tracting in  the  manner  just  described,  the  ethereal  solution  was  dried 
over  calcium  chloride,  the  ether  distilled  off,  and  the  liquid  residue 
fractionated ;  by  this  means,  24  grams  of  ethylic  ethylacrylate  were 
obtained  boiling  at  155—160°.  This  is  only  a  52  per  cent,  yield, 
which  is  accounted  for  by  the  fact  that  12  grams  of  some  substance 
of  higher  boiling  point  (270 — 280°)  was  abo  produced,  the  nature  of 
which  is  at  present  under  investigation. 

Ethylic  ethylacrylate  is  readily  saponified  by  alcoholic  potash,  yield- 
ing eihylacrylic  add  as  a  colourless,  oily  liquid,  with  pungent,  charac- 
teristic odour,  boiling  at  195 — 197°  under  atmospheric  pressure,  and 


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CONSTITUTION  OF  FATTY  ACIDS.     PART  I.  167 

showing  no  signs  of  solidification  even  when  cooled  to  - 14^.  The 
yield  of  pure  acid  is  41  per  cent,  of  the  amount  theoretically  obtain- 
able from  the  ethjlio  bromovalerate  employed. 

A  portion  of  the  add  was  converted  into  the  silver  salt  and 
analysed.    . 

0-3510  gave  01834  Ag.     Ag»  52-25. 

C5H702Ag  requires  Ag  =  52*17  per  cent. 

Oxidation  of  EihyUwrylic  Acid. — Fourteen  grams  of  the  acid  were 
oxidised  exactly  as  described  on  page  165,  firstly,  with  16  grams  of 
potassium  permanganate,  and  then  with  a  solution  of  45  grams  of 
potassium  dichxomate  dissolved  in  dilute  sulphuric  acid ;  the  mixture 
was  distilled  in  a  current  of  steam,  and  the  distillate,  after  neutralisation 
with  potassium  hydroxide,  was  evaporated  to  complete  dryness,  finally 
on  the  water-bath.  The  fatty  acids  obtained  on  distilling  the  residue 
with  concentrated  sulpburi^  acid  were  dried  by  standing  for  some 
time  in  contact  with  concentrated  sulphuric  acid,  and  then  fractionally 
distilled.  Eventually,  nearly  the  whole  of  the  acids  boiled  between 
137°  and  143°,  and  a  portion  boiling  at  140°  was  converted  into  the 
silver  salt  and  analysed. 

0-1914,  on  ignition,  gave  0-1 144  Ag.    Ag  =  5977. 

0-2386  gave  0-1744  CO^,  0-0640  H^O,  and  01420  Ag.     0  =  1992  ; 

H-2-97;  Ag«  59-51. 
OjHjCOOAg  requires  C  =  19-89 ;  H  «  276  j  A.g  =  5966  per  cent. 

The  fraction  boiling  between  137°  and  143°  was  then  converted  into 
the  anilide  by  heating  for  24  hours  with  twice  its  volume  of  pure 
aniline,  and  the  solid  product  was  repeatedly  crystallised  from  light 
petroleum  (b.  p.  80 — 100°),  from  which  it  separates  in  white,  glisten- 
ing plates  melting  at  102 — 103°  (compare  Crossley  and  Perkin,  Trans., 
1898,  73^  34). 

0-1814  gave  15-2  c.c.  moist  nitrogen  at  21°  and  762  mm.    N  =  9*56. 
CjHg-OO-NH-CeHg  requires  N  =  9-39  per  cent. 

These  data  prove  conclusively  that  the  acid  produced  by  oxidising 
ethylacrylic  add  m  the  manner  described  is  propionic  acid.  The 
amount  of  propionic  acid  obtained  was  5*5  grams,  which  corresponds 
with  a  53  per  cent,  yield  of  the  amount  theoretically  obtainable  from 
the  ethylacrylic  acid  used. 


I9chwbyrie  Acid  from  laobtUylcioetic  Acid. 

ProparotAon  qf  lactmfylaoetic  Acid. — ^This  acid  was  prepared  by  the 
condensation  of  ethylic  sodiomalonate  with  isobutylic  bromide,  and 

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168      CROSSLEY  AND  LE  StJEUR  :  CONSTITUTION  OF  FATTY  ACIDS. 

subsequent  distillatiou  of  the  product,  after  saponification  with  alco- 
holic potash.     The  acid  boiled  at  198—200''. 

Braminatian  of  Ischutylacetic  Acid, — Fifty-two  grams  of  the  acid, 
4 '8  grams  of  amorphous  phosphorus,  and  140  grams  of  dry  bromine 
were  treated  in  the  usual  manner.  Ethylic  a-iromisobuiylaeetate  was 
obtained  as  a  colourless,  pleasant  smelling  liquid  boiling  at  115^  under 
a  pressure  of  43  muL 

01530  gave  0-1296  AgBr.     Br  =  36-01. 

CgHjoBr-OOOCgHg  requires  Br  =  35-87  per  cent. 

The  yield  of  the  ethylic  salt  was  93  per  cent,  of  the  theoretical. 

Treatment  of  EthyUc  BromiaobutylcteeUUe  with  QuinoHne  or  Diethyl- 
aniline, — Eighty-five  grams  of  the  bromethylio  salt  were  treated  in 
two  portions  with  quinoline  exactly  as  described  on  page  164,  and  the 
unsaturated  ethereal  salt  was  distilled,  when  22  grams  were  obtained 
boiling  at  168 — 169°  at  the  ordinary  pressure.  As  this  is  only  42  per 
cent,  of  the  amount  theoretically  obtainable,  the  effect  of  diethyl- 
aniline  on  the  brom-ethereal  salt  was  tried,  when  the  yield  was  in- 
creased to  70  per  cent.  It  was,  however,  found  exceedingly  difficult  to 
get  rid  of  the  last  traces  of  halogen ;  and  even  after  a  third  treat- 
ment with  diethylaniline,  the  substance  did  not  give  good  results  on 
analysis.    Possibly  this  is  due  to  the  presence  of  traces  of  halogen. 

I.  01040  gave  0-2626  C02and  0-0966  HgO.    C-66-23;  H  =  10-31. 
n.  0-1670    „    0-3820  CO2   „   01416  HjO.    C-66-36;  H«  10-02. 
CfiH^-COOOgHfi  requires  C  =  67-60  ;  H  =  9-86  per  cent. 

Perkin  and  Goodwin  (Trans.,  1896,  69,  1471)  found  that  ethylic 
dimethylacrylate,  prepared  in  a  similar  manner,  did  not  give  good 
results  on  analysis,  but  no  explanation  of  the  fact  is  offered. 

When  hydrolysed  with  alcoholic  potash,  the  oily,  unpleasant  smell- 
ing liquid  boiling  at  169°  is  converted  into  ieopropylacrylie  aoid,  which 
is  a  colourless,  oily  liquid  of  exceedingly  unpleasant  odour,  boiling  at 
133°  (60  mm.)  ;  it  does  not  solidify  when  cooled  to  - 16°  The  yield 
is  61  per  cent,  of  that  theoretically  obtainable. 

The  silver  ecUt  is  a  white,  amorphous,  insoluble  precipitate*  On 
analysis,  it  gave  the  following  numbers. 

0*2636  gave,  on  ignition,  0-1232  Ag.    Ag  «=  48-68. 

O^HgOjAg  requires  Ags=4g-77  per  cent. 

Oxidation  qf  Ieopropylacrylie  Acid, — ^Twenty  grams  of  the  acid  were 
oxidised  with  30  grams  of  potassium  permanganate,  and  afterwards 
with  60  grams  of  potassium  dichromate  dissolved  in  dilute  sulphuric 
add,  and  worked  up  exactly  as  already  described  on  page  166 ;  after 
careful  fractionation  of  the  acid,  the  portion  boiling  at  163 — 164°  was 
converted  into  the  silver  salt  and  analysed. 

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DOOTSON:  DERIVATIVES   OF  ACETONE  BICARBOXYLIC   ACID.       169 

0-2044,  on  ignition,  gave  01134  Ag.     Ag«:  55*47. 

0-2154  gave  0-1900  CO^,  0-0682  H^O,  and  01198  Ag.     C  =  2410 ; 

H  =  3-52;  Ag:^  55-61. 
CsHf'OOOAg  requires  C  =  24-61 ;  H  =  3*59 ;  Ag»55-38  per  cent. 

The  remainder  of  the  acid  (b.  p.  152 — 158^)  was  converted  into  the 
anilide  which  crystaUised  from  light  petroleum  (b.  p.  80 — 100°)  in 
glistening,  feathery  needles  melting  at  104 — 105°  (compare  Trans., 
1898,  73,  34). 

0*1296  gave  10  c.c.  moist  nitrogen  at  20°  and  762  mm.    N=:8-84. 
CaHY'OO'NH'C^Hfi  requires  N  =  8-59  per  cent. 

The  acid  (50  per  cent,  yield)  produced  by  the  oxidation  of  isopropyl- 
acrylic  acid  was,  therefore,  isobutyric  acid,  and  the  oxidation  had  taken 
place  in  the  manner  expected. 

Chsmical  LaboratobTi 

St.  Thomab's  HosprrAL. 


XX. — Some  Halogen   Derivatives  of  Acetone  Dicarb- 
OQcylic  Acid.     Part  I, 

By  Fbxdebick  W.  Dootsok,  M.A. 

The  extremely  reactive  nature  of  the  hydrogen  atoms  of  acetone- 
dicarboxylic  acid,  C0(GH2*  COOn)^^,  has  already  been  shown  by  a 
long  series  of  experiments,  but,  so  far,  no  attempt  to  replace  them  by 
halogens  has  been  recorded.  This  is  the  more  remarkable,  since 
halogen  substitution  products  could  not  fail  to  lend  themselves  to 
reactions  which  would  yield  derivatives  not  easily  obtainable  by  other 
means.  The  present  paper  is  intended  as  a  preliminary  note  of 
investigations  undertaken  in  this  direction. 

Acetonedicarboxylic  acid  in  aqueous  solution  reacts  readily  with 
chlorine  and  bromine,  evolving  carbon  dioxide,  and  yielding  an  oil 
which  attacks  the  eyes,  and  which,  from  its  general  properties,  is 
probably  a  mixture  of  the  halide  derivatives  of  acetone.  The  inter- 
action of  these  halogens  with  the  ethylic  salt,  however,  proceeds 
smoothly  and  with  but  little  decomposition,  yielding  ultimately  ethylic 
tetrahalideacetonedicarboxylate. 

Ethylic  MrachloraeeUmedic(vrh(>xyl(Ue  is  easily  obtained  by  passing  a 
stream  of  dry  chlorine  into  ethylic  acetonedicarboxylate  ;  the  latter, 
prepared  by  the  action  of  hydrogen  chloride  on  an  alcoholic  solution 
of  the  acid  {AnndUn^  1891, 261,177),  is  sufficiently  good  for  the  purpose 
without  further  purification.     Hydrogen  chloride  is  freely  evolved, 


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170  DOOTSON  :  SOME  HALOGEN   DERIVATIVES  OP 

and  the  liquid  becomes  hot ;  the  operation  is  continued  until  chlorine 
is  no  longer  absorbed,  when  the  contents  of  the  flask  are  found  to 
have  increased  in  weight  by  about  65  per  cent.,  the  reaction  as  it 
approaches  completion  being  facilitated  by  heating  on  the  water-bath. 
The  heavy,  pale  yellow,  oily  product  is  fractionated  under  reduced 
pressure,  when  the  greater  part  of  the  liquid  distils  over  between 
180°  and  183°  (16  mm.  pressure) ;  this  fraction  is  nearly  pure  ethylic 
tetrachloracetonedicarboxylate.  A  readier  method  of  purification 
is  found  in  fractional  crystallisation.  On  cooling  in  a  freezing 
mixture,  a  nearly  solid  mass  is  obtained  which,  after  being  drained  by 
the  aid  of  the  filter  pump,  is  strongly  pressed  between  folds  of  bibulous 
paper ;  the  crystals  thus  obtained  are  practically  pure. 

Ethylic  tetrachloracetonedicarboxylate  is  very  soluble  in  cither, 
benzene,  alcohol,  chloroform,  carbon  bisulphide,  and  light  petroleum, 
but  insoluble  in  water.  On  recrystallisation  from  alcohol,  it  is 
obtained  in  large,  lustrous,  colourless,  rectangular  plates  or  leaves, 
which  melt  constantly  at  30 — 30*5°  (uncorr.). 

0-3660  gave  04220  COg  and  0-0947  H^O.     H  =  2-87  ;  C  =  31-44. 
0-3455    „     0-5860  AgOl.     01  =  41-87. 

CgHjoOl^Og  requires  0  =»  31-81 ;  H  =  2-94  ;  01  =  41  68  per  cent. 

Since  all  the  hydrogen  atoms  of  the  acid  radicle  have  been  dis- 
placed by  chlorine,  the  constitution  of  this  substance  is  without  doubt 
represented  by  the  formula  00(00l2- 00002H5)2. 

So  far  this  ethereal  salt  has  resisted  all  attempts  to  saponify  it. 
Odd,  dilute  aqueous  potash  seems  to  be  without  action ;  aqueous  soda 
or  potash,  on  warming,  liberates  alcohol,  but  the  acid  at  the  same  time 
decomposes  with  the  formation  of  oxalic  acid,  recognised  by  the 
insolubility  of  the  calcium  salt  in  acetic  acid,  by  a  melting  point 
determination  (104°  uncorr.),  and  by  a  titration  of  the  crystallised  acid. 
Sodium  ethoxide  in  alcoholic  solution  behaves  in  a  similar  manner, 
whilst  water,  hydrochloric  acid,  and  hydrobromic  acid  at  200^  are 
without  appreciable  effect. 

Action  of  AhohoUc  Potash, — ^If  a  cold  alcoholic  solution  of  potash 
be  slowly  poured  into  an  alcoholic  solution  of  the  ethylic  salt,  the 
contents  of  the  flask  being  kept  cold,  no  potassium  chloride  separates, 
but  af  fcer  a  short  time  a  copious  crop  of  colourless  crystals  is  obtained  ; 
these  are  exceedingly  soluble  in  water,  but  only  slightly  so  in  alcohol. 
An  analysis  showed  them  to  be  the  potassium  salt  of  diMorofnaiUmiG 
acid  (Oonrad  and  Bruckner,  Ber,,  1891,  24,  2993).  The  following 
numbers  were  obtained  on  analysis. 

0-2297  gave  0-1587  K2SO4.    K  =  3098. 
0-2159     „    0-2480  AgOL     01  =  28-42. 

OOl2(OOOK)2  requires  K  =  31-32 ;  01  =  2842  per  cent. 

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ACETONE  DICARBOXYLIC   ACID.      PART  I.  171 

The  mother  liqnor  from  these  crystals  was  diluted,  acidified,  and 
extracted  with  ether,  and  the  ethereal  solation  washed  with  water, 
dried  over  calcium  chloride,  and  evaporated,  when  a  liquid  with  a 
strongly  acid  reaction  was  left.  A  consideration  of  the  action  of 
ammonia  on  ethylic  tetrachloracetonedicarboxylate,  described  l)elow, 
ItoVes  no  room  for  doubt  that  this  liquid  is  diMoraceUc  acid.  Hence 
the  reaction  that  takes  place  is  represented  by  the  equation 

OqCCljCOOCjHj)^  +  3K0H  =  COl2(COOK)2  + 

CHClj-  COOK  +  202H5-  OH. 

AeHon  of  Aqveaus  Ammoiwa. — Ethylic  tetrachloracetonedicarb- 
oxylate dissolves  readily  in  aqueous  ammonia  with  evolution  of  heat, 
and,  on  standing,  a  bulky  crop  of  large,  colourless  crystals  separates, 
these,  on  being  recrystallised  several  times  from  hot  water,  are 
obtained  in  thin,  rhombic  leaves  or  plates,  which  melt  constantly  at 
204 — 205^  (unoorr.),  are  very  soluble  in  alcohol  and  hot  water,  and 
moderately  in  ether,  light  petroleum,  and  benzene.  From  the  melt- 
ing point,  although  this  is  somewhat  higher  than  that  found  by 
Conrad  and  Bruckner  (loe.  cU.),  and  on  analysis,  this  substance  was 
identified  as  diehloromalonamide. 

0-2083  gave  0-1596  COg  and  00472  H^O.    C  =  20-89  ;  H  =  2-51. 
0-1464     „     20-4  c.c.  nitrogen  at  18°  and  768  mm.     N  =  16-57. 
0-1470     „     21-1  c.c.  „  19-5°  and  750  mm.    N«  16-58. 

0-1624     „    0-2740  AgCl.   CI -41-75. 
CCl2(CONH5)2requiresC  =  2108;  H=.2-35;N  =  16-40;  Cl  =  41-42per  cent. 

The  mother  liquor  from  the  dichloromalonamide,  on  concentration, 
yielded  a  crop  of  crystals  which,  after  recrystallisation  from  hot  water, 
were  obtained  in  short,  thick,  colourless  needles  with  ill-defined  ends  ; 
these  crystals,  which  are  very  soluble  in  alcohol  and  hot  water,  and 
moderately  so  in  cold  water,  melted  sharply  at  98 — 99°  (uncorr.). 
This,  together  with  a  nitrogen  determination,  was  sufficient  to  identify 
them  as  dichloraeetamide  (Hantzsch  and  Zeckendorf,  Ber.,  1887,  20, 
1309). 

0-2000  gave  19-5  c.c.  nitrogen  at  17°  and  762  mm.     N  » 11*35. 
CHCI2CONH2  requires  N  =»  1 1  06  per  cent. 

From  these  results,  it  follows  that  the  interaction  of  ethylic  tetra- 
chloracetonedicarboxylate and  ammonia  must  be  represented  by  the 
following  equation. 

CO(CCljCOOC2H5)2  +  SNHg  =  CCl2(CONH2)2  + 

CHClg-  CONH2  +  2C2H5-  OH. 

From  the  above  experiments,  it  appears  that  tetrachloracetone- 
dicarboxylic  acid,  if  capable  of  existence  at  all,  must  be  a  very 

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172      YOUNG:   ACTION  OF  CHLOROSULPHONIC  ACID  ON  THE 

unstable  compound  towards  alkalis,  and  that  the  displacement  of 
hydrogen  atoms  by  chlorine  exercises  a  remarkably  modifying  influence 
on  the  nature  of  the  products  of  decomposition,  whilst  the  chlorine 
atoms  themselves  show  an  unexpected  degree  of  stability.  An 
attempt  to  obtain  condensation  products  by  the  interaction  of  the 
dipotassium  derivative  of  ethylic  acetonedicarboxylate  and  ethylic 
tetrachloracetonedicarboxylate  in  alcoholic  solution  was  unsuccessful, 
there  being  no  separation  of  potassium  chloride  evenaf  ter  long-continued 
boiling. 

The  action  of  bromine  on  ethylic  acetonedicarboxylate  is  very 
similar  to  that  of  chlorine,  hydrogen  bromide  being  freely  evolved 
and  the  liquid  remaining  almost  colourless.  After  adding  excess  of 
bromine  and  heating  for  some  time  on  the  water-bath,  the  contents 
of  the  flask  were  shaken  with  dilute  sodium  carbonate  solution  until 
the  colour  was  discharged,  extracted  with  ether,  and  the  ethereal 
solution  washed  several  times  with  small  quantities  of  water.  After 
drying  and  evaporating  the  ether,  a  pale  yellow  oil  was  left^  which 
became  very  viscid  in  a  freezing  mixture,  but  could  not  be  obtained 
crystalline.  The  reactions  of  this  oil,  although  not  identical  with, 
are  very  similar  to  those  of  ethylic  tetrachloracetonedicarboxylate, 
and  will  be  described  in  a  future  communication. 

Uniyebsitt  Chemical  Labobatory, 
Cambeidob. 


XXL — Action     of      ChlorosuVphonic     Acid      on      the 
Paraffins  and  other    Hydrocarbons  as    a  means 
of  Purifying   the  Normal  Paraffins, 
By  Sydney  Young,  D.Sc.,  F.R.S. 

In  a  paper  by  Dr.  F.  E.  Francis  and  myself  on  the  action  of  fuming 
nitric  acid  on  the  paraffins  and  other  hydrocarbons  (Trans.,  1898,  78^ 
932),  it  was  mentioned  that  Aschan  had  recently  observed  (^er.,  1898, 
31,  1801)  that  di-isopropyl  and  isopentane  are  rapidly  attacked  by 
chlorosulphonic  acid  at  the  ordinary  temperature.  Aschan  expressed 
the  intention  of  continuing  this  investigation,  and  we  suggested  that 
it  would  be  interesting  to  know  whether  chlorosulphonic  acid,  like 
fuming  nitric  acid,  acts  le^s  energetically  on  the  normal  paraffins  than 
on  isoparaffins  and  other  hydrocarbons  that  contain  a  :CH-group. 

It  occurred  to  me  that,  if  this  were  so,  it  was  not  improbable  thali 
chlorosulphonic  acid  might  be  a  useful  reagent  for  removing  small 
quantities  of  isoparaffins  and  methyl  derivatives  of  the  polymethylenes 
from  the  normal  paraffins  separated  by  fractional  distillation  from 

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PARAFFINS  AND  OTHER  HYDROCARBONS,  ETC.      173 

petroleam.  I,  therefore,  wrote  to  Prof.  Aschan  to  ask  him  whether 
he  had  made  any  observations  in  this  direction  ;  he  informed  me»  in 
reply,  that  he  was  chiefly  interested  in  the  '^  mechanism  "  of  the 
reaction,  and  that  he  wished  to  continue  the  investigation  from  this 
point  of  view  himself,  but  he  very  kindly  expressed  his  willingness 
that  I  should  compare  the  behaviour  of  the  normal  and  isoparaffins 
towards  chlorosulphonic  acid,  and  that  I  should  make  use  of  the 
reagent  as  a  means  of  purifying  the  paraffins. 

As  a  preliminary  experiment,  I  took  equal  small  quantities  of  pure 
normal  hexane  and  of  isohexane,  and  added  to  each  about  its  own 
volume  of  chlorosulphonic  acid.  The  difference  in  the  action  was  ex- 
ceedingly marked  ;  the  isohexane  became  warm,  and  in  a  few  moments 
bubbles  of  gaseous  hydrogen  chloride  were  rapidly  evolved ;  the  normal 
hexane,  on  the  other  hand,  did  not  rise  perceptibly  in  temperature, 
and  it  was  only  after  some  time  that  hydrogen  chloride  was  given  off. 
After  standing  all  night,  the  isohexane  had  entirely  disappeared,  but 
about  half  the  normal  hexane  was  still  left ;  the  chlorosulphonic  acid 
had  changed  to  a  dark,  tarry  oil,  much  blacker  and  thicker  in  the  case 
of  isohexane. 

Again,  pure  normal  octane  from  octylic  iodide  was  far  less  rapidly 
attacked  than  normal  octane  separated  from  American  petroleum  by 
distillation. 

In  order  to  find  whether  normal  paraffins  from  petroleum  could  be 
purified  by  means  of  chlorosulphonic  acid,  specimens  of  normal  heptane 
and  of  normal  octane  freed  from  aromatic  hydrocarbons  were  treated 
with  about  one-fifth  of  their  volume  of  the  acid  and  left  in  contact 
with  it  for  two  or  three  days,  until  the  reaction  had  ceased.  The 
dark  oil  was  in  each  case  separated,  and  the  remaining  hydrocarbon 
was  shaken  repeatedly  with  strong  sulphuric  acid  until,  on  dilution, 
the  acid  gave  no  turbidity  with  water.  The  hydrocarbon  was  washed 
with  water,  then  shaken  with  caustic  soda,  and,  lastly,  with  water 
again ;  it  was  dried  with  phosphorus  pentoxide  and  distilled  twice 
from  an  ordinary  distillation  bulb.  The  sp.  gr.  was  then  determined, 
and  the  treatment  with  chlorosulphonic  acid  repeated.  There  was 
not  a  sufficient  quantity  of  either  paraffin,  and  they  were  both 
too  impure,  to  begin  with,  to  allow  of  the  treatment  being  continued 
until  the  sp.  gr.  had  become  constant,  but  the  following  table  will 
show  that  the  normal  octane  was  obtained  nearly  pure  and  that  con- 
siderable progress  had  been  made  in  the  purification  of  the  normal 
heptane. 


VOL.  LXXVI.  ^N 


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174}         TOUNG  :  ACTION  OF  CHLOROSULPHONIC  ACID,  ETC. 


Normal  Octane, 

Sp.  gr.  074^         B.  p.  (760  mm.). 

Pure  from  octylic  iodide 0'71848  125-75^ 

Specimen     from     petroleum    before  "t  ^,,- .«,  f  collected  between  | 

treatment  with  chlorosulphonicacid  j  ^''^^^  \  125*2°  and  127'0°  J 

After  first  treatment    0-7308  125*2  —127-3° 

„    second    „            07224  1257  —1261° 

„    third       „            0-71956  125-75—125-95° 


Normal  Heptam^, 

Sp.  gr.  074^         B.  p.  (760  mm.). 

Pure  from  P{nu8  sabiniana 070048  98-45° 

Specimen     from     petroleum     before  1  r^.tjirvn     j  collected  between  | 

treatment  with  chlorosulphonicacid  J  |      98°  and  102°     j 

After  first  treatment    0*7319  99-1— 100*3° 

„     second     „  0-7223  99*1—  996° 

The  normal  heptane  must  have  contained  a  little  isoheptane  and  a 
large  amount  of  methjlhezam  ethylene,  and  the  normal  octane  a  little 
iso-octaneand  a  larger  quantity  of,  presumably,  dimethylhexamethylene. 
The  normal  octane  was  less  impure  than  the  normal  heptane,  and 
there  was  more  of  it  (about  50  grams  before  treatment  with  chloro- 
sul phonic  acid)  ;  it  was,  therefore,  possible  to  carry  the  purification 
farther,  and  there  can  be  little  doubt  that  if  the  quantity  had  been 
larger  the  impurities  might  have  been  completely  eliminated. 

Miss  Fortey  has  also  found  that  impure  hexamethylene  from  Galician 
petroleum,  boiling  at  a  somewhat  lower  temperature  than  the  pure 
substance,  and,  therefore,  containing  methylpentam ethylene  and 
possibly  some  low  boiling  heptane,  has  both  its  sp.  gr.  and  its  boiling 
point  raised  by  treatment  with  chlorosulphonic  acid. 

When  chlorosulphonic  acid  is  added  to  benzene,  a  violent  action 
takes  place,  and  torrents  of  hydrogen  chloride  are  evolved. 

The  results  obtained  are  sufficient  to  show  that  chlorosulphonic 
acid  in  the  cold,  like  fuming  nitric  acid  at  a  higher  temperature,  acts 
far  less  energetically  on  the  normal  paraffins  than  on  the  isoparaffins, 
the  methyl  derivatives  of  the  polymethylenes  or  on  benzene,  also  less 
energetically  on  the  polymethylenes  than  on  their  methyl  derivatives. 
Generally,  chlorosulphonic  acid  acts  more  energetically  on  hydro- 
carbons that  contain  a  :CH-group  than  on  others. 

There  is,  however,  some  action  on  the  normal  paraffins,  and  con- 
sequently there  is  considerable  loss  in  the  process  of  purification,  just 
as  there  is  with  fuming  nitric  acid.    In  order  to  obtain  the  pure 


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PERKIN:  OXIDATION   OF  SULPHOCAMPHTLIC  ACID.  175 

normal  paraffins  from  petroleum,  it  would  be  best,  before  subjecting 
tbem  to  the  action  of  chlorosulphonic  acid,  to  separate  them  more 
completely  from  other  hydrocarbons  by  fractional  distillation  than 
was  done  in  the  ease  of  normal  heptane  or  normal  octane. 

Ukivbrsity  College, 

BaiBTOL. 


XXII. — Oxidation  of  Sulphocamphylic  Acid. 

By  W.  H.  Pkbkin,  jun. 

When  sulphocamphylic  acid  is  oxidised  at  0°  with  potassium  perman- 
ganate, the  principal  product  is  a  beautifully  crystalline  substance 
which  melts  at  254^  and,  on  analysis,  gives  numbers  agreeing  with 
the  formula  Cj8^22^7  >  ^^  100^,  it  loses  one  molecule  of  water,  which 
is  probably  water  of  crystallisation,  and  is  converted  into  a  substance, 
C^gHg^O^  which  has  been  named  " dicampherylic  add" 

Dicampherylic  acid  is  a  dibasic  acid,  as  is  shown  by  the  analysis  of 
its  silver  salt,  O^gH^gAggOg,  and  of  its  methylic  salt,  OjgH|g(CH3)20g, 
its  formula  may,  therefore,  be  written  Oj0QjgO2(COOH)2.  The  acid, 
furthermore,  contains  two  ketonic  groups,  since,  with  hydroxylamine, 
it  yields  a  diozime,  Ci4Hig(CINOH)2(COOH)2,  and  is,  by  reduction 
with  sodium  amalgam,  converted  into  tetrahydrodicampheryUo  ctctd, 
C^4Hjg(CH'OH)j(COOH)2 ;  its  formula  may,  therefore,  be  developed  to 
Ci4Hjg(CO)2(COOH)2.  The  most  interesting  property  of  dicampherylic 
acid  is  its  decomposition  by  concentrated  sulphuric  acid  at  85^,  when 
it  is  converted  almost  quantitatively  into  an  acid  of   the  formula 

^18^20^6  =  2C9H10O8. 

The  determination  of  the  nature  of  the  acid,  CgHi^Og,  was  found  to 
be  a  problem  of  considerable  difficulty,  but  its  constitution  was  ultim- 
ately established  by  the  consideration  of  the  following  facts. 

This  acid  is  a  monobasic  acid,  giving  well  characterised  salts,  of 
which  the  silver  aaltf  C^Hf^AgOg,  the  beautifully  crystalline  methylic 
aalt,  G^H^iOR^Y)^  and  the  ethylio  salt,  Cja.Q{0^'H.^)Osy  were  analysed, 
and  since,  on  treatment  with  acetic  anhydride,  it  is  converted  into  an 
acetyl  campoundy  C9Hg(OC2HgO)02,  it  is  evident  that  it  is  a  hydroxy. 
carboxylic  acid  of  the  composition  CgHg(OH)*COOH. 

When  exposed  to  the  action  of  bromine  vapour,  the  acid,  by  substi- 
tution, yields  a  dibroTno-derivative,  CgHgBr2(0H)-C00H,  in  which  the 
bromine  is  so  firmly  united  that  boiling  with  potash  does  not  eliminate 
it,  a  behaviour  which  indicates  that  the  acid  belongs  to  the  aromatic 

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176  PERKIN  :   OXIDATION  OF  SULPHOCAMPHYLIC  ACID. 

series.  This  supposition  is  confirmed  by  the  fact  that  nitric  acid  con- 
verts the  acid  into  a  dinitro-derivative,  CgHg(N02)2(OH)-COOH,  an 
interesting  substance  which  behaves  like  a  dibasic  acid,  since  its 
silver  salt,  which  crystallises  in  dark  red  needles,  has  the  formula 
CgH^AgjNjOy,  and  is  evidently  produced  by  the  substitution,  not  only 
of  the  hydrogen  of  the  carboxyl  group,  but  also  that  of  the  hydroxyl 
group,  by  silver,  that  is,  its  formula  may  be  written 
C3He(N02),(OAg)-COOAg. 

This  behaviour  is  quite  usual  in  aromatic  hydroxy-acids  containing 
two  nitro-groups.  Thus,  for  example,  3  :  5-dinitrohydrocumaric  acid, 
OH- CgH2(NOg)2-CH2-CH:3-OOOH,  yields  a  dibasic  silver  salt  crystal- 
lising in  dark  red  needles,  and  1:3:  5-dinitroparahydroxybenzoic  acid, 
OH*CgH2(N02)j'COOH,  a  dibasic  salt  crystallising  in  brown  needles. 
From  these  results,  it  was  evident  that  the  acid  O^H^qO,  was  either  a 
hydroxydimethylbenzoic  acid,  OH- CgH2(CH3)2*  COOH,  or  a  hydroxy- 
ethylbenzoic  acid,  OH*  CgH3(02H5)'COOH  ;  it  could  not  be  a  hydroxy- 
hydrocumaric  acid,  OH'CgH^-CHg-OHg'COOH,  since  the  three  iso- 
meric (o-,  m-,  p-)  forms  of  this  acid  are  known,  and  melt  respectively 
at  83°,  IIP,  and  129°,  whereas  the  acid  CgHj^Os  melts  at  204°  In 
order  to  determine  whether  it  contained  an  ethyl  group  or  two  methyl 
groups,  it  was  decided  to  endeavour  to  oxidise  the  acid.  Before  doing 
this,  however,  it  was  necessary  to  protect  the  hydroxyl  group  by  con- 
verting it  into  a  methoxy-group,  and  this  was  readily  accomplished  by 
treating  the  methylic  salt  of  the  acid  with  sodium  methylate  and 
methylic  iodide  in  the  usual  way.     The  oily  methylic  salt, 

OOHj-OgHg-COOOHj, 
thus  formed  yielded,  on  hydrolysis,  the  corresponding  methoxy-acid, 
OCHg'CgHg*  COOH,  and  this,  on  oxidation  with  permanganate,  was 
almost  quantitatively  converted  into  an  acid  of  the  formula 
OCH3-C7Hg(OOOH)2,  showing  that  the  original  acid,  CqEL^qO^,  must 
have  contained  two  methyl  groups,  one  of  which  had  been  converted 
into  COOH  during  the  oxidation ;  in  short,  the  acid  CgHj^Og  is  a 
dimethylhydroxybenzoic  acid,  OH-CgH2(CH3)2'COOH. 

On  heating  the  methoxydibasic  acid,  OCH3'C7H4(OOOH)j,  with 
hydriodic  acid,  the  corresponding  hydroxy-acid,  OH*C7Hg(COOH)2, 
was  obtained  as  a  very  sparingly  soluble,  crystalline  powder  melting 
at  283°,  and  giving,  in  alcoholic  solution,  an  intense  reddish-violet 
coloration  with  ferric  chloride.  As  these  properties  are  the  same  as 
those  of  the  hydroxymethylterephthalic  acid  of  the  formula 

COOH 

ACH 
OH" 


COOH 

Digitized  byCjOOQlC 


perkin:  oxidation  of  sulphocamphylio  acid.       177 

described  by  Jacobsen  and  H.  Meyer  {Ber.,  1883,  16,  191),  the 
author  at  first  thought  that  the  acids  were  identical  (compare  Froc., 
1893,  9, 110). 

The  experiments  up  to  this  stage  were  completed  in  1893,  and 
since  then,  during  the  course  of  a  long  investigation  into  the  pro- 
perties of  sulphocamphylic  acid,  some  new  facts  were  discovered  which 
made  it  improbable  that  this  formula  could  be  correct. 

The  subject  was  therefore  further  investigated,  and  after  much  labour 
the  relative  positions  in  the  hydrozydimethylbenzoic  acid,  CgH^^Og,  and 
also  in  the  hydroxymethyldicarboxylic  acid,  OH-CgHj(CH3)(COOH)2, 
produced  by  its  oxidation  have,  as  the  author  believes,  been  clearly 
established. 

In  the  first  place,  the  acid,  CqBL^qOq,  which  melts  at  204^  and  gives 
no  colour  with  ferric  chloride,  is  isomeric  with  the  already  known 
hydroxydimethylbenzoic  acids,  as  will  be  seen  from  the  following 
table,  in  which  the  numbers  refer  to  the  groups  taken  in  the  order 

CH,:OH.:OH:COOH. 

'  ^  M.  p. 

oriho'HydriKBypM'aicylie  acid  1:2:5:4 
i^riho-HydrooBymeaitylenic  acid  1 !  3  :  4  :  5 
parorMydraxymesitf/lenic  acid  1:3:2:5 
a-Hydroocyxylic  add  1:3:1:4 

P'  u  »  1:4:2:3 

T  »  »  1:4:5:2 

The  careful  investigation  of  the  acid  CgHj^Os,  melting  at  204^,  has 
clearly  established  the  following  points. 

1 .  J%e  Hydroxyl  Group  i$  in  the  Afetorpoai^ion  relatively  to  the  Carhoxyl 
Grotip. — That  the  acid  is  not  an  orthohydroxy-acid  is  clearly  indicated 
by  the  fact  that  it  gives  no  colour  with  ferric  chloride ;  that  it  is 
neither  an  or^hydroxy-  nor  a  ^xirahydroxy-acid  is  shown  by  the  fact 
that  it  may  be  heated  with  concentrated  hydrochloric  acid  or  hydriodic 
acid  at  200 — 220^  without  decomposition,  whereas  ortho-  and  para- 
hydroxy-acids  are  readily  decomposed  into  the  corresponding  phenols 
and  carbonic  anhydride  by  this  treatment. 

^  2.  The  Acid  w  derived  from  the  Xylmud,  [(CH3)2 :  OH  =  1 :  2  : 6].— 
When  the  calcium  salt  of  the  acid  CgH^^Og  is  distilled  with  lime,  it 
shows  the  behaviour  characteristic  of  the  calcium  salts  of  meta- 
hydroxy-acids,  namely,  decomposition  takes  place  with  great  difficulty, 
and  only  at  an  exceedingly  high  temperature.  The  distillate  contains 
a  xylene],  which  crystallises  from  water  in  long,  colourless  needles, 
and  the  aqueous  solution  of  which  gives,  with  ferric  chloride,  a  dis- 
tinct, although  not  intense,  bluish-violet  coloration ;  it  melts  at  75^ 
and  distils  constantly  at  218^  The  identity  of  this  xylenol  was,  with 
difficulty,  established   in  the  following  way.      All  the  six  possible 

Digitized  by  VjOOQIC 


199° 

FeCl,,  bluish-violet. 

179 

FeCl,,  intense  blue. 

223 

FeClg,  brown. 

170 

144 

153 

178 


perkin:  oxidation  of  sulphocamphylic  acid. 


xy lends,  CgH3(CH3)2*OH,  have  been  prepared  and  carefully  in- 
vestigated, 80  that  their  properties  are  well  known;  and  in  order 
to  clearly  show  how  the  constitution  of  the  zylenol  from  the  acid 
CgHjoOg  was  proved,  a  short  table  of  the  properties  of  the 
zylenols  is  appended,  the  numbers  referring  to  the  groups  in  the 
order  CHg :  CH3 :  OH. 


I 

1:8:6 

b.  p.  219 -S* 

m.  p.  68* 

Fed,,  no  colour. 

II 

1:2:6 

„     218 

„    76 

,,      violet 

Ill 

1:4:2 

„     211-6 

,,    76 

„      no  colour. 

IV 

1:2:4 

»     226 

»     66 

„      not  stated. 

V 

1:8:4 

„     211-6 

»     26 

„     blue. 

VI 

1:8:2 

„     212 

„    49 

„     not  stated. 

Three  of  these  zylenols,  namely,  Nos.  Ill,  lY,  and  Y,  were  obtained  from 
Schuchardt,  and  after  very  careful  purification  found  to  be  different 
from  the  author's  zylenol,  as,  indeed,  the  melting  and  boiling  points 
would  indicate.  Since,  again,  both  the  melting  point  and  boiling  point 
of  No.  YI  differ  markedly  from  those  of  the  author's  zylenol,  there  re- 
main only  Nos.  I  and  II  as  possibly  representing  its  constitution,  and  of 
these,  No.  II  is  the  more  probable,  since  this  melts  and  boils  at  ezactly 
the  same  temperatures,  whereas  No.  I  has  a  lower  melting  point,  and  is 
stated  to  give  no  coloration  with  ferric  chloride.  As,  however,  very 
slight  traces  of  impurity  considerably  depress  the  melting  point  of  the 
zylenols,  and  as  the  colour  with  ferric  chloride  is  not  pronounced  in  the 
case  of  any  one  of  them,  it  was  necessary  to  obtain  further  evidence 
before  deciding  this  question  of  identity.  Fortunately,  there  is  a  wide 
difference  in  the  melting  points  of  the  tribromo-zylenols  derived  from 
Nos.  I  and  II,  that  from  the  former  melting  at  166°,  whereas  that  from 
the  latter  melts  at  184°,  and  on  trying  the  ezperiment  with  the  author's 
zylenol  it  was  found  that  its  tribromo-derivative  melted  sharply  at 
184° ;  there  can,  therefore,  be  no  doubt  that  the  constitution  of  this 
zylenol  is  represented  by  the  formula  Cq'K^{CH^)2'0^'^  1:2:6. 

Since,  then,  the  acid,  On*C0H2(CH3),*  COOK,  from  which  this 
zylenol  was  obtained  is  a  metahydrozy-aoid,  it  can  only  have  the 
formula  OeH2(CH3)2(OOOH)-OH=  1 : 2  : 4  : 6  ;  that  is,  it  is  metahydr- 
axypouraaaylic  (leid^  and  closely  allied  to  arthohydroxi/paraasylic  ctcid, 
[1:2:4:6],  which  Renter  (Ber,^  1878,  11,  30)  prepaxed  by  fusing 
pseudocumenesulphonic  acid  with  caustic  potash  (compare  Jacobsen, 
Ber.,  1899,  12,  436).  This  is  the  second  occasion  on  which  a 
derivative  of  pseudocumene  has  been  obtained  indirectly  from  sulpho- 
camphylic  acid,  as  Koenigs  and  Meyer  {Ber.,  1894,  27,  3468,  [com- 
pare Trans.,  1898,  p.  840)  found  previously  that  isolauronic  acid  was 
readily  converted  into  parazylic  acid  by  the  action  of  sulphuric  acid. 

The  hydrozy-dibasic  acid,  produced  indirectly  by  the  ozidation  of 


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PERKIN:   OXIDATION   OF   SULPHOCAMPHYLIC  ACID.  179 

metahydrozyparaxylio  acid  as  described  above,  is  evidently  an  ortho- 
hydrozy-acid,  since  its  alcoholic  solution  gives  an  intense  blue 
coloration  with  ferric  chloride;  it  can,  therefore,  only  be  a 
hydrozymethylterephthalic  acid  of  the  formula 

0H-0eHj(CH3)-CX)0Ha  [CHj-COOH :  OH :  COOH  =  1:3:5:6], 

and  the  difference  between  this  formula  and  that  originally  assigned 
to  this  add  (see  p.  176)  is  simply  in  the  position  of  the  hydrozyl 
group. 

Unfortunately,  like  so  many  other  instances  in  which  benzene  com- 
pounds have  been  obtained  from  cafnphor  and  its  derivatives,  the 
formation  of  metahydrozyparazylic  acid  throws  very  little  light  on  the 
constitution  of  dicampherylio  acid,  from  which  it  is  so  readily  pro- 
duced, and  although  it  would  be  easy  to  suggest  a  formula  for 
the  latter  acid,  the  author  prefers  not  to  do  so  until  further  experi- 
mental data  are  forthcoming. 

With  regard  to  the  formation  of  such  benzene  derivatives  as  xylene, 
cymene,  pseudocumene,  carvacrol,  acetylortho-xylene,  and  others  from 
camphor,  and  of  derivatives  of  paratoluic  acid  and  parazylic  acid  from 
camphoric  acid,  the  author  entirely  shares  the  opinion,  somewhat 
differently  expressed  by  Ascban,*  namely,  that  until  we  understand 
the  extraordinary  mechanism  of  the  production  of  these  benzene 
derivatives,  their  formation  is  of  little  value  in  determining  the 
constitution  of  the  substances  from  which  they  are  derived. 

The  author  is  much  indebted  to  Messrs.  B.  Prentice,  J.  L. 
Heinke,  F.  H.  Lees,  and  others  for  their  valuable  assistance  in  the 
experimental  part  of  this  investigation. 

The  author  also  wishes  to  state  that  the  heavy  cost  of  the  very  large 
amount  of  material  used  in  this  research  was  to  a  very  considerable 
extent  covered  by  repeated  large  grants  from  the  Government  Grant 
Fund  of  the  Koyal  Society. 

EXPSBIMENTAL. 

OxidtUian  of  Sulpkocamphylic  Acid.    Formation  of  Dic(vmpherylic  Add, 

CisHjoOe  +  HjO. 

In  carrying  out  this  oxidation,  sulphocamphylic  acid  in  quantities 
of  60  grams  was  dissolved  in  about  1  litre  of  water,  the  solution 
neutralised  with  potassium  carbonate,  and  transferred  to  a  flat 
porcelain  basin  in  which  a  turbine  was  fitted.  The  solution  was 
cooled  to  (P  by  adding  powdered  ice,  and  a  cold  saturated  solution 

*  Straetur  nad  steraochenuache  Sta<li«ii  in  der  Camphergrnppe ;  Helsingfors, 
1895,  p.  17. 


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180  PERKIN:   OXIDATION   OF   SULPHOCAMPHYLIC   ACID. 

of  potassium  permaDganate  run  in  slowly  until  the  colour,  which 
instantly  disappears  at  first,  just  remained  permanent,  care  being 
taken  that  the  whole  was  well  stirred  and  the  temperature  kept  below 
2°  during  the  operation.  The  product  from  several  such  oxidations 
was  filtered,  the  filtrate  and  washings  of  the  manganese  precipitate 
evaporated  to  a  small  bulk,  and  the  concentrated  yellow  solution 
acidified  and  allowed  to  stand  overnight;  the  yellow,  crystalline 
precipitate  which  had  separated  was  collected,  washed  with  water, 
and  purified  by  repeated  crystallisation  from  dilute  acetic  acid ;  the 
magnificent,  lemon-yellow  prisms  thus  obtained,  after  standing  for 
some  days  on  a  porous  tile  in  contact  with  air,  gave  the  following 
results  on  analysis. 

01216  gave  0-2767  00^  and  00712  HgO.     0  =  61-83;  H  =  6-60. 

01410    „     0-3190  COj    „    00806  HjO.    0  =  6170;  H  =  6-36. 

01524     „     0-3448  OOj    „    0-0894  HjO.     0  =  61-70;  H  =  6-61. 

OigHjjOy  requires  0  =  61  71 ;  H  =  6-28  per  cent. 

These  crystals,  when  heated  for  a  long  time  at  100^  gradually  lose 
water,  a  change  which  takes  place  rapidly  at  120 — 130°.  1  '0952  grams 
of  the  substance,  dried  in  the  air,  lost  0-0610  gram  at  100",  or  5 '47 
per  cent,  whereas  the  calculated  loss,  supposing  O^gEEgs^r  ^  ^ 
converted  into  O^gH^oO^  at  100°,  is  5-14  per  cent.  An  analysis  of  the 
substance,  dried  at  120°  until  of  constant  weight,  gave  the  following 
result. 

0-1496  gave  0-3571  00^  and  00851  Kfi.     0  =  6510;  H  =  6-32. 
OigHgoOg  requires  0  =  6506  ;  H  =  6-02  per  cent. 

The  molecular  weight  of  this  substance  was  determined  by  the 
cryoscopic  method,  when  it  was  found  that  0*8010  gram,  dissolved  in 
36-1  grams  of  acetic  acid,  depressed  the  melting  point  0*26°,  this 
corresponding  with  a  molecular  weight  332,  whereas  the  molecular 
weight  of  OigHj^jOg  is  332  and  of  OigHj^Oy  350. 

On  long  standing  in  an  uncorked  flask,  the  solution  used  in  this 
determination  deposited  a  mass  of  slender,  colourless  needles  which 
looked  like  threads  of  asbestos  and  quite  unlike  the  hard  prisms  in 
which  the  substance  OigH^^O^  usually  crystallises.  An  analysis 
showed,  however,  that  the  crystals  had  the  composition  O^gHjgO^. 

0-1028  gave  0-2328  00^  and  0-06  H^O.     0  =  61*76  ;  H  =  6-48. 
OigHjaOy  requires  0  =  61*71 ;  H  =  6*28  percent. 

These  results,  taken  together  with  those  described  in  the  following 
pages,  show  that  the  product  of  the  oxidation  of  sulphocamphylic  acid 
is  a  substance  of  the  formula  O^gH^oO^,  which  crystallises  with  water 
in  prisms  of  the  composition  O^gHg^O^. 

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PERKIN  :   OXIDATION    OF  SULPHOCAMPHYLIC  ACID.  181 

This  compound,  which  has  been  named  dicampherylic  acid,  melts  at 
about  254^,  and  is  readily  soluble  in  alcohol,  acetone,  acetic  acid,  and 
ethylic  acetate,  but  only  very  sparingly  in  benzene;  it  is  almost 
insoluble  in  cold  water,  although,  in  a  finely  divided  state,  it  dissolves 
appreciably  in  boiling  water,  and  separates  on  cooling  in  almost 
colourless,  prismatic  crystals.  It  dissolves  readily  in  dilute  sodium 
carbonate,  and,  although  the  well-cooled  solution  does  not  decolorise 
permanganate,  it  does  so  readily  on  warming. 

Dicampherylic  acid  dissolves  readily  in  warm,  concentrated  nitric 
acid,  and,  on  boiling,  oxidation  takes  place  so  slowly  that  even  after 
10  minutes  the  addition  of  water  causes  a  large  quantity  of  the 
substance  to  separate  unchanged.  Fuming  hydriodic  acid  dissolves 
the  finely-powdered  crystals  easily,  and  if,  after  boiling  for  a  short 
time,  the  bulk  of  the  hydriodic  acid  is  distilled  off,  the  residue,  on 
mixing  with  water,  deposits  a  heavy,  dark  brown  oil  which  becomes 
colourless  on  the  addition  of  sulphurous  acid  and  smells  like  isoamylic 
iodide. 

Salts  of  Dicampherylic  Acid. 

That  this  acid  is  a  dibasic  acid  was  first  shown  by  titrating  a 
weighed  quantity  of  the  anhydrous  crystals  with  standard  alkali, 
when  it  was  found  that  0*4416  required  for  neutralisation  0'1495 
gram  KOH,  or  33*8  per  cent.,  whereas  a  dibasic  acid  of  the  formula 
C^gHg^Og  requires  33*7  per  cent. 

The  silver  salt  was  obtained  as  a  white,  gelatinous  precipitate  on 
adding  silver  nitrate  to  a  warm,  neutral  solution  of  the  ammonium 
salt,  the  precipitate  on  warming  with  much  water  for  about  an  hour 
becomes  crystalline,  and  is  then  readily  filtered  and  washed.  The 
analyses  seem  to  show  that  this  salt,  after  drying  over  sulphuric  acid 
in  a  desiccator,  has  the  formula  CigHg^AgjOy,  and  that  at  120—130° 
it  loses  water,  and  then  has  the  formula  Cj^H^gAggO^. 

The  silver  salt,  dried  over  sulphuric  acid  in  a  desiccator,  gave  the 
following  results  on  analysis. 

0-2064  gave  0*2833  CO2,  0*0696  H^O,  and  0*0790  Ag.    C  =  37*66  ; 

H  =  3*77j  Ag- 38*46. 
0*2469  gave  0*3420  00^,  0*0746  ttjO,  and  00963  Ag.     0  «  3777  ; 

H  =  3*36;  Ag«  38*68. 
0*3390  gave,  on  ignition,  0-1 302  Ag.     Ag  »  38*41. 
CigHj^gjO^  requires  C  »  38*29.     H  =  3*66 ;  Ag  =  38*29  per  cent. 

This  salt  may  be  heated  at  120 — 130°  without  decomposition,  and 
after  its  weight  had  become  constant  it  was  analysed. 


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182  PERKIN;  OXiDATION  OF  SULPHOCAMPHYLIC  ACIB. 

0-2260  gave  03223  OO^,  0-0681  H^O,  and  0-0887  Ag.      0  =  38-89 ; 

H=3-35;  Ag  =  39-24. 
0-22,  on  ignition,  gave  0-0860  Ag.     Ag  =  3909. 
CigHigAgjOj  requires  0  =  3956  ;  H  =  3-30;  Ag= 39*56  per  cent. 

A  neutral  solution  of  the  ammonium  salt  of  dicampherylic  acid 
gives  a  heavy,  white  precipitate  with  lead  acetate,  but  no  precipitate 
with  barium,  calcium,  or  zinc  chlorides ;  copper  acetate  gives  no  pre- 
cipitate in  the  cold,  but  on  boiling  a  light  blue,  crystalline,  copper  salt 
separates. 

Meihylic  Diccbmpherylate,  CiqH.^q{C'H^}20^. — ^This  salt  was  prepared 
by  two  different  methods. 

1.  The  dry  silver  salt  of  the  acid  was  digested  for  2  hours  with  ether 
and  excess  of  methylic  iodide,  and  the  ethereal  solution  filtered ;  the 
residue  was  extracted  repeatedly  with  ether,  and  the  combined 
ethereal  solutions  evaporated  to  a  small  bulk.  On  standing,  beautiful 
crystals  separated  which,  after  crystallisation  from  benzene,  melted  at 
226—227°. 

2.  The  acid,  dissolved  in  methylic  alcohol,  was  mixed  with  con- 
centrated sulphuric  acid  and  heated  to  boiling  on  a  water-bath  for 
a  few  minutes ;  on  cooling,  glistening  crystals  separated,  which,  after 
collecting,  and  recrystallising  from  benzene,  melted  at  226 — 227°. 
This  substance,  which,  like  all  the  derivatives  of  dicampherylic  acid,  is 
very  difficult  to  bum,  was  analysed,  with  the  following  results. 

I.  01692  gave  0-4120  OO2  and  01040  HjO.   0  =  66-42;  H  =  6-83. 
n.  01652     „     0-4011  OO2    „    0-0996  HjO.   0  =  66-22;  H  =  6-69. 
III.  0-1663     „     0-4027  OO2    „    01007  HjO.    0  =  66  04;  H  =  6-73. 
Oi8Hi8(OH8)20^  requires  0  =  66  66 ;  H  =  6-66  per  cent. 

In  No.  I,  the  methylic  salt  used  was  prepared  from  the  silver  salt, 
and  in  Nos.  II  and  III  from  the  acid  by  treatment  with  methylic  alcohol 
and  sulphuric  acid. 

Action  qf  ffydroacf/lcmUne  on  Dicampherylie  Acid, 

In  studying  the  action  of  hydroxy lamine  on  dicampherylic  acid,  the 
pure  acid  (2  grams),  dissolved  in  dilute  potash  (6  grams),  was  mixed  with 
hydroxy  lamine  hydrochloride  (2  grams),  and  acidified  after  12  hours, 
when  the  nearly  pure  oxime  separated  in  white  flocks.*  The  whole 
was  extracted  with  much  ether,  the  ethereal  solution  rapidlyf  dried 

*  In  this  form,  the  oxime  is  readily  soluble  in  ether,  and  also  in  warm  water,  bat 
after  crystallisation  from  ether,  it  becomes  almost  insoluble,  both  in  this  solvent 
and  in  water. 

t  If  this  operation  is  not  very  quickly  performed,  the  oxime  is  apt  to  separate  on 
the  lumps  of  calcium  chloride. 


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PERKIN  :  OXIDATION  OF  SULPHOCAMPHYLIC  ACID.  L83 

with  calcium  chloride,  filtered,  and  allowed  to  stand  either  as  it  was, 
or,  better,  after  concentrating  somewhat,  when  the  ozime  separated  in 
crystalline  crusts.  These  crusts,  after  washing  with  ether,  gave  the 
following  results  on  analysis. 

I.  01420  gave 0-3090  CO2  and  00830  H^O.    C  =  5935  ;  H  =  650. 

IL  0-1548  „  0-3362  00,  „  0-0914  HgO.  0  =  59-23 ;  H  =  6-57. 
ni.  01699  „  0-3663  OOj  „  0-0986  HjO.  0  =  58-80;  H  =  6-44. 
IV.  01608    „     0-3487  OOj    „    00937  H^O.    0  =  5914;  H  =  6-47. 

V.  0-2602     „     17-4  c.c.  nitrogen  at  18°  and  758  mm.    N  =  7-70. 
Other  nitrogen  determinations  gave  N  =  6'90,  7*30,  and  7*05. 

OigHjjNaOg  requires  0  =  59-66  ;  H  =  607 ;  N  =  773  per  cent. 

This  substance  is,  therefore,  the  dioxime  of  dicampherylic  acid  produced 
according  to  the  equation 

CisHjoOo  +  2KH,-0H  -  O.gHjoO.CN-OH),  +  2H,0. 
When  heated  in  a  capillary  tube,  the  ozime  turns  brown  at  210 — 220°, 
and  gradually  becomes  darker  as  the  temperature  rises,  but  does  not  melt 
completely  at  250°.  It  is  almost  insoluble  in  ether  and  most  organic 
solvents,  but  dissolves  in  concentrated  hydrochloric  acid,  and  is  re- 
precipitated  unchanged  when  the  solution  is  diluted  with  water  and 
warmed;  it  dissolves  also  in  caustic  potash  solution,  and  is  repre- 
dpitated  unchanged  by  hydrochloric  acid. 

Action  qf  Acetic  Anhydride  on  the  Dioxime.-— -The  pure  dioxime 
dissolves  slowly,  but  completely  in  cold  acetic  anhydride,  and  if  the 
solution  is  allowed  to  remain  in  contact  with  air,  a  crystalline  cake 
gradually  forms ;  this,  after  recrystallisation  from  dilute  acetic  acid, 
gave  the  following  results  on  analysis. 

0-1524  gave  0-3130  OOj  and  0  0800  HgO.    0  =  560  ;    H  =  6-83. 
0-1277    „    0-2640  OO2    „    0-0702  H^O.     0  =  5638;  H  =  6-ll. 
0-2106     „     12-4  C.C.  nitrogen  at  18°  and  742  mm.     N  =  663. 
Oj^jHjjjNjOj  requires  0  =  56-87  ;  H  =  6-13 ;  N  =  6-63  per  cent. 

This  substance,  which  is  doubtless  the  (iceicUe  of  iha  dioxime, 
OjgH^gNjO^O^H^O,,  melts  at  184°,  and  crystallises  from  dilute  acetic 
acid  in  microscopic  needles;  when  heated  at  190 — 200°,  it  froths  up 
and  emits  an  odour  of  acetic  anhydride.  Dilute  potash  hydrolyses  this 
acetate,  and  on  acidifying  and  extracting  with  ether  in  the  usual  way, 
the  characteristic  crusts  of  the  regenerated  dioxime  are  obtained. 

0-3153  gave  22*5  c.c.  nitrogen  at  22°  and  758  mm.     N  =  8-06. 
OigHjjN^O^  requires  N  »  7*73  per  cent. 


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184       perkin:  oxidation  op  sulphocamphylic  acid. 

Action  of  Phenylhydraaine  on  DicamfJierylic  Add, 

When  dicampherjlic  acid  (3*6  grams)  is  mixed  with  freshly-distilled 
phenylhydrazine  (5  grams)  and  glacial  acetic  acid  (10  grams),  and  the 
mixture  heated  on  the  water-bath,  reaction  sets  in  in  a  short  time  with 
evolution  of  gas,  the  liquid  soon  becomes  dark-red,  and  after  20 
minutes  crystals  begin  to  separate.  As  soon  as  the  separation  appears 
to  be  complete,  the  whole  is  filtered  hot  on  a  platinum  cone,*  and  the 
crystals  washed  with  acetic  acid  and  recrystallised  from  this 
solvent.  The  ruby-red  crystals  thus  obtained  are  very  difficult  to 
bum,  and  for  this  reason  several  analyses  were  made^  with  the 
following  results. 

01487  gave  0'3736  COg  and  00820  HgO.  0  =  68-50  ;  H  =  6-13. 
0-1735  „  0-4333  CO2  „  00957  HgO.  0  =  68-16;  H  =  6-I3. 
0-1562  „  0-3873  OO3  „  0  0908  HjO.  0  =  6762;  H  =  6-46. 
01963     „    18-5  C.C.  nitrogen  at  21°  and  753  mm.     N  =  10*64. 

These  analytical  numbers  agree  best  with  the  formula  OjoHg^N^Og, 
which  would  be  obtained  by  the  combination  of  1  mol.  of  dicam- 
pherylic  acid  and  2  mols.  of  phenylhydrazine  with  loss  of  water, 
Oi8H2oOe  +  20eH5-NH-NH2  =  C3oH8^NP5  +  H20,  or  it  is  possible  that 
it  is  the  dihydrazone  of  O^gHgoOg  crystrallising  with  IHjO. 

This  substance  dissolves  in  hot  acetic  acid  or  alcohol,  forming  yellow 
solutions  which,  on  cooling,  deposit  brilliant,  ruby-red  crystals.  When 
heated  in  a  capillary  tube,  it  darkens  at  230°,  and  decomposes  with 
evolution  of  gas  and  charring  at  237°.  It  dissolves  in  alkalis  and 
alkali  carbonates,  forming  yellow  solutions,  which,  on  acidifying,  give 
a  bright  yellow  precipitate,  consisting,  apparently,  of  the  unchanged 
substance. 


Reduction  qf  Dicampherylic  Acid.     FormcUion    of  Tetf^hydrodieam- 
pherylic  Acid,  O^^'H^^fio' 

In  order  to  investigate  this  reduction,  pure  dicampherylic  acid  was 
dissolved  in  dilute  soda  and  treated  in  a  flat  basin  with  a  large  excess 
of  sodium  amalgam  (5  per  cent.),  and  after  24  hours,  the  whole 
was  neutralised,  filtered,  and  the  filtrate  acidified  and  extracted 
many  times  with  ether.  The  ethereal  solution,  after  drying  and  con- 
centrating, deposited  the  greater  part  of  the  product  of  reduction  in 
crystalline  flakes.  These  were  collected,  washed  with  ether,  and 
analysed. 

*  The  mother  liquors  when  heated  with  more  phenylhydrazine  give  another 
crop  of  crystals. 


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PERKIN:  OXIDATION   OF  SULPHOCAMPHYLIC   ACID.  185 

01683  gave  0-3966  COj  and  O'l  126  H^O.     C  =  6409  ;  H  =  7-43. 

0-1600    „     0-3497  CO2    „    0-1003  HgO.     C  =  63-58  ;  H=  7-42. 

0-1616    „     0-3816  CO3    „    0^080  H2O.     0  =  6444  ;  H  =  7-43. 

CigHg^Og  requires  C  =  64-28 ;  H  =  7*14  per  cent. 

The  determination  of  the  molecular  weight  of  this  acid  by  the  boiling 
point  method,  using  alcohol  as  the  solvent,  gave  298,  307,  and  296, 
whereas  the  calculated  molecular  weight  for  C^^K^fiQ  is  336. 

Tetrahydrodicampherylic  acid  melts  at  about  297 — 298°  with 
evolution  of  gas.  It  is  sparingly  soluble  in  methylic  and  ethylic 
alcohols  and  acetic  acid  in  the  cold,  and  in  boiling  water,  and  is 
not  readily  soluble  even  in  boiling  acetic  acid  ;  but  from  its  solution 
in  dilute  acetic  acid  it  separates,  on  long  standing,  in  four-sided  plates. 

Silver  TetrcLhydrodicwnpherylate, — ^When  a  hot,  dilute  solution  of 
the  ammonium  salt  of  the  acid  is  mixed  with  silver  nitrate,  a 
white  precipitate  is  formed,  and  if  this  be  rapidly  removed  with 
the  aid  of  the  pump,  the  filtrate,  on  standing,  deposits  beautiful  groups 
of  colourless  crystals  of  a  silver  salt;  this,  on  analysis,  gave  the 
following  numbers. 

0-2169  gave  0-3070  COj,  00826  HgO,  and  00846  Ag.       C  =  3860  ; 
H=4-18;  Ag  =  39-0. 
CjgHggAggOe  requires  0  »  39*27 ;  H  =  4-0 ;  Ag  =  3927  per  cent. 

Fusion  of  DicampheryHc  Acid  with.  Potash. 

Fifteen  grams  of  the  pure  acid  was  mixed  with  60  grams  of  potash 
and  a  little  water,  and  heated  at  about  120°,  when  the  crystals  rapidly 
dissolved,  forming  a  dark  solution,  which  readily  crystallised  owing  to 
the  separation  of  a  potassium  salt.  On  raising  the  temperature,  the 
liquid  became  dark  brown,  and  then  red,  and  after  much  frothing  sud- 
denly solidified  at  about  165°,  a  peculiar  aromatic  smell  being  noticeable ; 
more  potash  (20  grams)  was  then  added,  and  the  temperature  gradually 
raised,  until,  at  250°,  the  frothing  had  entirely  ceased.  The  melt  was 
dissolved  in  water,  acidified,  and  extracted  10  times  with  ether,  the 
ethereal  solution  evaporated,  and  the  viscid  residue,  which  smelt 
strongly  of  fatty  acids,  distilled  in  a  current  of  steam.  The 
strongly  acid  distillate,  when  neutralised  with  pure  calcium  carbonate 
and  concentrated,  deposited  beautiful,  feathery  crystals  of  calcium 
isobutyrate ;  these  were  collected  and  analysed. 

DetermiTuUion  of  Water  of  Cryatallisation,* — 0*2426  gram,  on  heat- 
ing at  100°  until  constant,  lost  00674  gram  H20«  27*79. 

{OJELjO^^CsL  +  Q'ELfi  requires  H20  =  29*60  per  cent. 
*  Compare  Croesley  and  Perkin,  Trans.,  1898,  78,  15. 


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186         PEBKIN  :  OXIDATION  OP  SULPHOCAMPHYLIC  ACID. 

01752  gave  0-1107  OaSO^.    Ca=  18-58. 

(08H/COO)2Ca  requires  Ca  =  18-67  per  cent. 

The  remainder  of  the  calcium  salt  was  dissolved  in  water,  acidified 
with  hydrochloric  acid,  and  the  oily  acid  which  separated  extracted 
with  ether ;  the  dried  ethereal  solution,  after  the  ether  had  been  re- 
moved on  the  water-bath,  left  an  oily  residue  of  isobutyric  acid  which 
distilled  at  154—165°. 

01684  gave  0-3347  00^  and  0-1368  HgO.     0  =  54-21 ;  H  =  908. 
CgH^COOH  requires  0  =  54*54 ;  H  =  909  per  cent. 

This  acid,  which  is  undoubtedly  isobutyric  acid,  is  formed  in  con- 
siderable quantities  during  this  fusion,  as  the  amount  obtained  from 
15  grams  of  dicampherylic  acid  could  hardly  have  been  less  than 
3  grams. 

The  residue  in  the  distilling  flask,  after  the  isobutyric  acid  had  been 
removed  by  steam,  contained  a  flocculent  precipitate ;  this  was  removed 
by  filtration,  and  the  filtrate  extracted  five  times  with  ether.  The 
ethereal  solution,  on  evaporation,  deposited  9  grams  of  an  almost 
colourless,  thick,  oily  acid,  which  showed  no  signs  of  crystallising, 
even  after  standing  for  some  weeks  over  sulphuric  acid.  On  analysis,  it 
gave  the  following  numbers. 

01535  gave  0-3364  OOj  and  0-0842  H^O.     0  =  5977 ;  H  =  6-ll. 
CgHioO^  requires  0  =  59*34 ;  H  =  5-50  per  cent. 

In  the  hope  of  obtaining  this  acid  in  a  crystalline  condition,  it 
was  converted  into  its  lead  salt,  by  adding  lead  acetate  to  its 
aqueous  solution,  and  the  white  precipitate,  which  looked  almost 
crystalline,  was  suspended  in  water  and  decomposed  by  hydrogen 
sulphide;  the  filtrate,  after  concentration,  was  extracted  with  pure 
ether,  <Sec.,  in  the  usual  way,  and  the  residue,  on  being  allowed  to  remain 
over  sulphuric  acid  in  a  vacuum  desiccator,  left  a  colourless,  syrupy 
acid  which,  on  analysis,  gave  the  following  results. 

0-1753  gave  03785  OOj  and  0-0953  HgO.     0  =  5888 ;  H  =  6-05. 
0-1418    „    0-3086  OOj    „    0  0774  H^O.     0  =  59-35 ;  H  =  6-05. 
OjjHioO^  requires  0  =  59-34  ;  H  =  5-50  per  cent. 

The  silver  salt,  which  was  obtained  as  a  white,  amorphous  precipi- 
tate on  adding  silver  nitrate  to  a  neutral  solution  of  the  ammonium 
salt,  gave  the  following  results  on  analysis. 

0-2157  gave  0-2184  00^,  0-0469  HgO,  and  0-1173  Ag.     0  =  27-61  ; 

H  =  2-41;  Ag  =  54-38. 
Oj^HgAgjO^  requires  0  =  27*28  ;    H  =  2-02  ;  Ag  =  54*54  per  cent. 

This  acid,  which  appears  to  have  the  formula  Q*jB^{GO0Ti)^,  is  very 

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PERKIN:  OXIDATION  OF  STJLPHOCAMPHTLIC  ACID.  187 

readily  soluble  in  water;  when  heated,  it  gives  a  yellow  distillate 
which  is  insoluble  in  cold  water,  but  dissolves  on  boiling,  and  there- 
fore very  probably  consists  of  the  anhydride.  The  solution  of  the 
add  in  sodiom  carbonate  does  not  decolorise  permanganate  at  ordinary 
temperatures  except  on  long  standing. 

It  should  be  mentioned  that,  in  one  experiment  on  the  fusion  of 
dicampherylic  acid  with  potash,  a  small  quantity  of  an  acid  was  ob- 
tained which  was  almost  insoluble  in  water,  and  only  very  sparingly 
■olnble  in  boiling  glacial  acetic  acid.  This  acid,  which  crystallised 
from  acetic  acid  in  needles  and  melted  above  300^,  was  at  first  thought 
to  be  terephthalic  acid,  but  this  is  not  the  case,  since  its  methylic  salt 
is  a  syrup. 

Metahydroocyparaxylte  Acid,  CgHj(CHg),(COOH)-OH  [=1:2:4:6]. 

This  acid,  as  stated  in  the  introduction,  is  formed  by  the  action  of 
concentrated  sulphuric  acid  at  85^  on  dicampherylic  acid.  The  finely- 
divided  acid  dissolves  readily  in  warm,  concentrated  sulphuric  acid, 
forming  a  yellow  solution  which,  if  heated  at  80 — 85^,  gradually 
becomes  darker,  the  decomposition  of  the  dicampherylic  acid  being 
complete  in  about  10  minutes.  On  pouring  the  product  into  water,  an 
ochreous  precipitate  separates  which  is  collected  on  the  pump,  washed 
well  with  water,  dissolved  in  dilute  sodium  carbonate,  boiled  with 
animal  charcoal,  filtered,  and  the  acid  reprecipitated.  The  now 
almost  colourless  acid  is  further  purified  by  recrystallisation,  first 
from  glacial  acetic  acid,  and  then  from  water. 

01462  gave  0-3483  CX)^  and  00803  H^O.     C  =  6497  ;  H  =  610. 

01402     „    0-3360  COj,    „     0  0773  HjO.     0  =  65-36 ;  H  =  613. 

01268     „     0-3023  OO2    „     0  0721  H^O.     0  =  65-02;  H  =  6-31. 

CgHjoOg  requires  0  -  65*06  ;  H  =  6-03  per  cent. 

Metahydroxyparaxylic  acid  melts  at  203 — 204%  and  when  strongly 
heated,  as,  for  example,  during  the  combustion,  a  portion  chars,  but  the 
main  quantity  sublimes  in  beautiful,  colourless  crystals.  It  is  readily 
soluble  in  alcohol  and  ether,  moderately  so  in  hot  water  and  in  glacial 
acetic  acid,  but  only  sparingly  in  chloroform,  light  petroleum,  benzene, 
carbon  bisulphide,  and  cold  water ;  its  aqueous  solution  gives  no  colora- 
tion with  ferric  chloride.  From  glacial  acetic  acid,  it  crystallises  beauti- 
fully in  nearly  colourless,  glistening  plates,  which,  on  exposure  to  the 
air,  become  opaque  and  chalky,  a  change  which  takes  place  rapidly  at 
100^ ;  from  water,  the  acid  also  crystallises  well.  Hydroxyparaxylic 
acid  does  not  react  with  hydroxylamine,  and  is  not  reduced  by 
sodium  amalgam  at  the  ordinary  temperature,  or  when  its  solution 
in  hydriodic  add  is  boiled  for  some  time ;  at  200 — 220°,  however, 

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188       perkin:  oxidation  of  sulphocamphylic  acid. 

fuming  hydriodic  acid  and  phosphorus  slowly  attack  it,  with  forma- 
tion of  a  small  quantity  of  a  neutral  substance  of  phenolic  nature, 
but  even  at  this  temperature  most  of  the  acid  remains  undecomposed. 
The  great  stability  of  the  acid  is  furthermore  clearly  shown  from  the 
following  experiment. 

1'5  grams  of  the  pure  acid  was  heated  with  10  c.c.  of  concentrated 
hydrochloric  acid  at  230 — 235°  for  8  hours ;  the  tube  contained  a 
good  deal  of  charcoal,  and  the  greenish  liquid,  which  had  a  phenolic 
odour,  was  filled  with  long,  silky  needles  like  asbestos  threads  ;  these 
crystals  were  collected  and  purified  by  dissolving  in  potash,  filtering, 
and  reprecipitating  with  hydrochloric  acid  ;  the  substance  then  melted 
at  202°,  and  consisted  of  unchanged  hydroxyparaxylic  acid,  as  the 
following  analysis  shows. 

01 395  gave  03320  COg  and  0-0778  HgO.     0  =  64-92  ;  H  =  6-19. 
CgHioOg  requires  C  =  6606  ;  H  =  603  per  cent. 

The  amount  of  acid  recovered  in  this  experiment  was  1  '1  grams. 

Salts  of  Hydroxypckraxylic  Acid, 

The  silver  salt,  CgHgAgOg,  was  obtained,  on  adding  silver  nitrate 
to  a  neutral  solution  of  the  ammonium  salt,  as  a  white,  amorphous 
precipitate.  It  decomposes  readily  on  heating,  yielding  a  beautifully 
crystalline  sublimate.  The  following  results  were  obtained  on 
analysis. 

01736  gave  0*2486  COg,  00548  H2O,  and  0*0680  Ag.     C  =  3906  ; 

H  =  3-61;  Ag  =  3918. 
0-1562  gave  0-0617  Ag.     Ag  =  39-50. 

CgH^AgOg  requires  0  =  3956;  H  =  330  ;  Ag  =  39-66. 

The  neutral  solution  of  the  ammonium  salt  of  hydroxyparaxylic 
acid  gives  no  precipitate  with  calcium*  or   barium  chlorides. 

Methylic  Hydroxyparaayylate,  OH- CgH2(CH3)2- COOCH3.— In  order 
to  prepare  this  salt,  the  acid  (22  grams),  dissolved  in  methylic  alcohol 
(160  c.c),  was  mixed  with  concentrated  sulphuric  acid  (40  c.c.)  and 
heated  to  boiling  for  half  an  hour;  more  sulphuric  acid  (10  c.c.)  was 
then  added,  the  boiling  continued  for  half  an  hour,  and  the  whole 
allowed  to  stand  overnight.  The  beautiful,  striated,  leaf -like  crystals 
which  separated  wete  collected  with  the  aid  of  the  pump,  and,  after 
washing  with  water  and  drying  at  100°,  were  found  to  weigh  13*8 
grams.  The  brown  mother  liquors,  on  diluting  with  water,  deposited 
a  brown  oil  which,  on  shaking  and  stirring,  slowly  solidified ;  this 
crude  product,  after  washing  and  drying  on  a  porous  plate  at  100°, 

*  For  a  description  of  the  calcium  salt  of  hydroxyparaxylic  acid,  see  p.  192. 

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PERKIN:  OXIDATION  OF  SULPHOCAMPHYLIC  ACID.  189 

weighed  7*5  grams.  Each  portion  was  separately  crystallised  from 
henzene,  and  in  this  way  17  grams  of  the  pare  methylic  salt  was 
obtained,  showing  that  the  acid  is  easy  to  etherify. 

0-1763  gave  0-4300  COg  and  01087  ttjO.     C  =  66*52  ;  H  ==  6-86. 
01544    „    0-3772  COg    „    00939  HjO.     C  =  66-67  ;  H- 6-76. 
CioHigOj  requires  C=  66*66 ;  H  =  6-66  per  cent. 

Methylic  hydroxypcwaosylcUe  melts  at  148 — 149^  and  in  its  other 
properties  closely  resembles  the  corresponding  ethylic  salt. 

Bthylie  hydroxyparaxylate,  OH- CoHj(CH3)2*  COOCjHg.— This  was 
prepared  by  treating  the  acid  with  ethylic  alcohol  and  sulphuric  acid 
in  the  same  way  as  the  methylic  salt. 

The  colourless  needles  obtained  by  crystallisation  from  light  pet- 
roleum melted  at  134 — 135^,  and  gave  the  following  results  on 
analysis. 

0-1309  gave  0-3270  CO,  and  00891  H^O.     C  =  68-13 3  H  =  756. 

0-1590    „    0-3962  CO3    „    0-1010  H^O.     0-67-94;  H  =  7*06. 

C^jHiPg  requires  0  =  68-04 ;  H  =  7*22  per  cent. 

Ethylic  hydroxyparaxylate  is  readily  soluble  in  alcohol  and  benzene, 
but  rather  sparingly  in  light  petroleum  ;  its  solution  in  alcohol  gives 
no  coloration  with  ferric  chloride. 

It  is  insoluble  in  sodium  carbonate,  but  dissolves  readily  in  caustic 
potash  solution,  and  is  reprecipitated  unchanged  on  the  addition  of 
acid.     When  heated  in  small  quantities,  it  distils  unchanged. 

Aeetaxyparastylic  Acid,  G^lS.j^CR^)j^OQ^fiyOOQiR. 

In  order  to  prepare  this  substance,  hydrozyparaxylic  acid  (1  gram) 
was  boiled  with  acetic  anhydride  (10  grams)  in  a  reflux  apparatus  for 
half  an  hour,  and  the  product,  when  cold,  was  shaken  with  water 
until  the  excess  of  anhydride  had  been  removed. 

The  acetyl  compound,  which  separated  as  a  crystalline  cake,  was 
purified  by  recrystallisation,  first  from  methylic  alcohol  and  then  from 
benzene. 

0-1556  gave  0*3612  COg  and  00810  H^O.     0  =  63*30 ;  H  ==  5-78. 

0-1642    „     0-3805  COj    „    0-0870  HjO.     C==6319 ;  H  =  5-88. 

C11H12O4  requires  0=*  63-46  ;  H=*5-77  per  cent. 

Acetoxyparaxylic  acid  crystallises  in  colourless,  stellate  groups,  melts 
at  141 — 142^,  and  when  rapidly  heated  in  small  quantities  it  distils 
with  only  very  slight  decomposition.  It  is  readily  soluble  in  benzene, 
alcohol,  and  ethylic  acetate,  but  almost  insoluble  in  light  petroleum ; 
it  dissolves  with  difficulty  in,  and  is  only  very  slowly  hydrolysed  by, 

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190  PERKIN:  OXIDAlTION   OP  SULPHOCAMPHYLIC  ACID. 

boiling  water,  but  is  readily  decomposed  by  boiling  with  potass- 
ium carbonate  solution,  and,  on  acidifying,  pure  hydroxyparazylic 
acid  separates. 

CH, 
Dinitrohyd/raocyparaxylic  Add,  ^^  I        \k[(\. 


COOH 

When  pure  hydroxyparazylic  acid  is  added^  in  small  quantities  at 
a  time,  to  strong  nitric  acid,  it  hardly  dissolves,  and  no  change  takes 
place  until  the  mixture  is  gently  warmed,  when  suddenly  a  vigorous 
action  sets  in,  the  substance  passes  into  solution,  and  each  fresh  quantity 
added  dissolves  with  a  slight  hissing  sound  and  abundant  evolution  of 
red  fumes.  In  a  short  time,  beautiful,  yellow  crystals  separate,  and 
after  cooling  and  mixing  with  an  equal  bulk  of  water,  further  pre- 
cipitation takes  place.  The  yellow  crystals  were  collected,  washed 
with  water,  recrystallised  from  this  solvent  and  analysed,  with  the 
following  results. 

01818  gave  0-2838  COg  and  0'0562  H2O.     C  =  42-57 ;  H  =  3-43. 
01637     „     0-2535  002     „    0-0496  H^O.     0  =  42-23 ;  H  =  336. 
0-1996     „     19-2  c.c.  nitrogen  at  22*^  and  764  mm.    N=  10-81. 
0H-0e{0H3)2(N02)2-000H  requires  0  =  42-19;  H  =  3-12;  N=  10*94  per  cent. 

Dinitrohydroxyx)araxylic  acid  is  readily  soluble  in  alcohol,  acetone, 
ethylic  acetate,  and  acetic  acid,  moderately  so  in  hot  water,  but  only 
sparingly  in  cold  water,  benzene,  and  chloroform.  It  crystallises  from 
water  in  glistening,  yellow  plates,  and  dissolves  in  dilute  sodium 
carbonate,  forming  a  deep  orange  solution.  When  heated  in  a  capillary 
tube,  it  darkens  at  195°,  and  decomposes  rapidly  at  203 — 205°  with 
evolution  of  gas. 

SaiUs  of  Dinitrohydroxypwaxylic  Add. 

Tlie  Silver  Salt,  0Ag*0^(0H3)2(N02)2*000Ag.— When  silver  nitrate 
is  added  to  a  moderately  concentrated  and  slightly  alkaline  solution  of 
the  ammonium  salt  of  the  acid,  no  precipitate  is  produced  at  first,  but, 
on  standing,  a  splendid,  dark  purple,  crystalline  silver  salt  separates, 
which,  under  the  microscope,  is  seen  to  consist  of  fern-like  groups  of 
needles.  As  this  salt  appeared  to  be  explosive,  the  silver  was  deter- 
mined by  heating  the  substance  with  nitric  acid  and  hydrochloric  acid 
in  a  sealed  tube  at  180°  and  weighing  the  silver  chloride  formed. 

01466  gave  0-0892  AgOl.     Ag  =  45-70. 

OgH^Ag^NgOy  requires  Ag  =  45-95  per  cent. 


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PKBKIN:   OXIDATION   OF   SULPHOCAMPHYLIC  ACID.  191 

This  analysis  shows  that,  in  the  formation  of  this  salt,  the  hydrogen 
of  the  hjdroxyl  group,  as  well  as  that  of  the  carhoxyl  group,  has 
been  replaced  by  silver  (see  p.  176).  This  silver  salt  is  moderately 
easily  soluble  in  warm  water,  and  may  be  recrystallised  from  this 
solvent,  but,  apparently,  with  a  good  deal  of  decomposition. 

The  faintly  alkaline,  dilute,  orange-coloured  solution  of  the  am- 
monium salt  of  dinitrohydrozyparaxylic  acid  gives  no  precipitate  with 
copper  aeekUef  barium  chloride,  or  zinc  acektte,  but  lead  acetate  produces 
a  very  sparingly  soluble,  heavy,  yellow  precipitate,  and  ferric  chloride 
a  brownish-red  precipitate. 


Dibromhydroxi/paraxylio  Acid,         ^ 


The  action  of  bromine  on  hydroxyparaxylic  acid  was  investigated  in 
the  following  way  :  3*9608  grams  of  the  pure,  finely  powdered  acid 
was  exposed  in  a  glass  dish  to  the  action  of  bromine  vapour  for  12 
hours,  during  which  time  much  hydrogen  bromide  was  produced ;  after 
removing  the  excess  of  bromine  by  exposure  over  solid  potash  in  a 
vacuum  desiccator,  it  was  found  that  3*6932  grams  of  bromine  had 
been  absorbed.     Eepresenting  the  reaction  by  the  equation, 

Cj^io^g  +  2Br2  =  Q^^Brfi^+  2HBr, 

the  increase  in  weight  should  have  been  3*769  grams. 

A  determination  of  the  bromine  in  this  crude  substance  gave  the 
following  result. 

0-2378  gram  gave  0*2698  AgBr.     Br  »  48*27. 

CgHgBrjOj,  requires  Br* 49*38  per  cent. 

It  is  difficult  to  crystallise  the  crude  substance,  and  the  only  way 
this  could  be  accomplished  was  to  dissolve  it  in  a  little  methylic  alcohol, 
add  a  good  deal  of  chloroform,  and  evaporate  to  a  small  bulk  to  remove 
most  of  the  methylic  alcohol ;  if,  now,  more  chloroform  is  added  and, 
after  rapidly  concentrating,  the  liquid  is  allowed  to  stand,  the  super- 
saturated solution  rapidly  deposits  well-shaped,  prismatic  crystals, 
which,  on  analysis,  gave  the  following  results. 

0-1836  gave  0-2246  COj  and  0*0428  H,0.     C  =  33*37  ;  H  =  2*58. 
0-3218     „     0-3726  AgBr.     Br  =  49  26. 
C^HgBrjOg  requires  0  =  33*33  ;  H  =  2*47  ;  Br  =  49*38  per  cent. 

IHbromhydroxyparaxylic  acid  melts  at  204 — 205^  and  is  very  readily 
Bolnble  in  alcohol,  but  only  sparingly  in  chloroform ;  when  pure,  it 
crystallifles  well  from  dilute  alcohol. 

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192       perkin:  oxidation  of  sulphocamphylic  acid. 

It  is  a  very  stable  substance,  and  may  be  boiled  for  some  time  with 
caustic  potash  without  decomposing. 

A  determination  of  the  molecular  weight  of  this  bromo-acid  by 
Raoult's  method^  using  acetic  acid  as  the  solvent,  gave  M  =  333| 
whereas  the  value  calculated  from  the  formula  CgHgBrjOg  is  324. 


CH3 

l:2-Xylenol(6) 


oh/^H3 


This  zylenol  is  produced,  as  explained  in  the  introduction,  when  the 
calcium  salt  of  hydroxyparaxylic  acid  is  distilled  with  lime. 

The  calcium  salt  was  prepared  by  boiling  finely  divided  hydroxy- 
paraxylic acid  (30  grams)  with  water  and  a  slight  excess  of  pure 
calcium  carbonate,  filtering,  and  evaporating  nearly  to  dryness,  when, 
on  standing,  the  calcium  salt  separated  in  warty  masses. 

The  dried  salt  was  finely  powdered,  mixed  intimately  with  slaked 
lime  (50  grams),  and  distilled  in  small  quantities  from  small  retorts 
over  a  blow-pipe,  as  great  heat  is  necessary  to  bring  about  the  de- 
composition. The  distillate,  which  was  an  aqueous  liquid  containing 
dark-coloured,  semi-solid  masses  and  smelling  very  strongly  of  phenol, 
was  mixed  with  a  slight  excess  of  caustic  soda,  decolorised  by  boiling 
with  animal  charcoal,  filtered,  and  the  filtrate  acidified  with  hydro- 
chloric acid.  The  oily  precipitate  solidified  rapidly  and  almost  com- 
pletely, and  after  collecting,  washing,  and  spreading  on  a  porous  plate, 
an  almost  colourless,  crystalline  mass  (3  grams)  was  obtained.  On 
submitting  this  to  distillation,  nearly  the  whole  passed  over  at  218^ 
(760  mm.)  as  a  colourless  oil  which,  on  cooling,  at  once  solidified.  The 
distillate,  dissolved  in  a  considerable  quantity  of  water  at  70°,  on 
slowly  cooling,  deposited  very  long,  colourless  needles,  which  were 
dried,  first  on  a  porous  plate  and  then  at  60%  and  analysed. 

0-1415  gave  0-4075  OOj  and  0-1053  H^O.     C- 78-54  ;  H=.8-27. 
CgH3(CH8)2-OH  requires  0=  78*69  ;  H  =  8-19  per  cent. 

This  substance,  which  has  been  found  to  be  1  : 2'Xylenol{Q),  melts  at 
74—75°,  and  is  moderately  soluble  in  hot  water;  its  cold,  saturated, 
aqueous  solution  gives  a  distinct,  although  not  intense,  bluish-violet 
coloration  with  ferric  chloride,  and,  on  standing,  the  solution  rapidly 
becomes  opaque  (compare  Tohl,  Ber,,  1885, 18,  2562;  Nolting  and  Forel, 
ibid.,  p.  2673). 

Tribromo-xylenol,  C^Br3(CH3)j*OH. — ^This  substance,  which  has 
already  been  described  by  Tohl  {loc,  cit.),  was  prepared  by  adding  about 
0*5  gram  of  the  xylenol  obtained  in  the  above  experiment,  in  small 

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PERKIN:  OXIDATION  OF  SULPHOCAMPHYLIC  ACID.  193 

quantities  at  a  time,  to  3  grams  of  bromine,  care  being  taken  to 
moderate  the  vigorous  reaction  by  cooling;  after  2  hours,  the 
product  was  poured  on  to  a  glass  dish,  'and  left  over  potash  in  a 
desiccator  until  the  excess  of  bromine  had  been  removed,  the  residue 
being  purified  by  recrystallisation  from  the  dilute  alcohol. 

0-2840  gave  04440  AgBr.    Br.  =  66-62. 

CgHyBrgO  requires  Br  =  66-86  per  cent. 

This  tribromo-zylenol  crystallises  from  dilute  alcohol  in  long,  pale- 
yellow  needles  which  melt  at  184^,  and  it  thus  agrees  in  its  properties 
with  the  tribromo-derivative  which  Tohl  obtained  by  brominating 
l:2-xylenol(6). 

MMMyparaxylio  Acid,  [(CHg)^  :  OOOH  :  OCHg  -1:2:4:6]. 

With  the  object  of  obtaining  further  information  as  to  the  constitu- 
tion of  the  acid  CgHj^Og,  now  known  to  be  hydrozyparazylic  acid,  it 
was  decided  to  endeavour  to  oxidise  one  or  more  methyl  groups,  and 
in  order  to  do  this  it  was  necessary,  in  the  first  instance,  to  protect  the 
hydroxyl  group  in  the  usual  way,  namely,  by  substituting  methyl  or  ethyl 
for  hydrogen.  For  this  purpose,  in  the  first  experiments,  the  methylic 
salt  of  the  acid  (16  grams)  was  mixed  with  a  solution  of  sodium 
(2  grams)  in  methylic  alcohol  and  methylic  iodide  (26  grams),  and  the 
mixture  heated  first  at  96 — 110°  for  2  hours,  and  afterwards  at 
120 — 130°  for  2  hours.  The  light-brown  product  was  evaporated 
on  the  water-bath,  water  added,  and  the  heavy  oil  extracted  with 
ether ;  the  ethereal  solution,  on  evaporation,  deposited  an  oil  which  did 
not  show  any  signs  of  crystallising,  and  which,  doubtless,  consisted  of 
the  methylic  salt  of  methoxyparaxylic  acid,OOH:3-OgH2(CH:3)2'OOOCH3. 
This  was  not  analysed,  but  at  once  hydrolysed  by  boiling  with  excess 
of  methyl  alcoholic  potash  for  2  hours  ;  after  evaporating  the  methylic 
alcohol,  and  acidifying  the  aqueous  solution  of  the  residue,  a  very 
bulky,  white  precipitate  was  obtained,  which  was  purified  by  re- 
crystallisation  from  60  per  cent,  alcohol. 

0-1376  gave  0-3366  00^  and  0-0823  HgO.    C  =  66-66  ;  H  =  664. 
CgH2(CH3)2(OCH3)-COOH  requires  0  =  66-66  ;  H-6-66  per  cent. 

Methoxyparaxylic  acid  melts  at  170 — 171°,  and  distils  at  a  high 
temperature,  apparently  without  decomposition.  It  is  very  sparingly 
soluble  in  hot  water,  and  almost  insoluble  in  cold  water ;  it  crystallises 
from  boiling  water  in  woolly  masses  consisting  of  fine  needles.  It  is 
readily  soluble  in  acetic  acid,  methylic  alcohol,  chloroform,  and  ethylic 
acetate,  but  only  sparingly  in  carbon  bisulphide  and  light  petroleum ;  it 
crystallises  splendidly  from  ethylic  acetate  in  long,  colourless  prisms. 

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194  PERKIN  :  OXIDATION  OF  SULPHOCAMPHYLIC  ACID. 

Ethylie  Ethoxupa/raxylate,  O0fi^<^^^{GR^^*QOO0^^. 

This  was  prepared  by  heating  ethylie  hydroxyparaxylate  (2  grams) 
with  sodium  (0*26  gram)  dissolved  in  alcohol,  and  ethylie  iodide 
(5  grams)  at  120 — 130°  for  2  hours,  evaporating  the  product  on  the 
water-bath,  and  adding  water,  when  an  oil  separated  which  rapidly 
solidified.  The  crystalline  mass  was  collected,  washed  with  water,  left 
in  contact  with  porous  porcelain  until  free  from  oil,  and  recrystallised 
from  dilute  methylic  alcohol,  when  glistening  prisms  were  obtained 
which  gave  the  following  results  on  analysis. 

0'1496  gave  03841  COg  and  0-1110  HgO.     C- 70-02  ;  H=.8'24. 
CijHigOg  requires  C  =  70-27 ;  H  =  8-11  per  cent. 

Ethylie  ethozyparaxylate  melts  at  50 — 5P,  and  is  readily  soluble  in 
methylic  alcohol,  light  petroleum,  benzene,  ohloroform,  and  carbon 
bisulphide. 

Ethoxypa/raxylic  Acid,  OG^K^^OoK^iGlI^^^COOK. 

When  boiled  with  alcoholic  potash,  ethylie  ethozyparaxylate  is 
readily  hydrolysed,  and  if  the  product  is  mixed  with  water  and  evapo- 
rated until  free  from  alcohol,  the  addition  of  hydrochloric  acid  to  the 
cold  aqueous  solution  precipitates  the  acid  as  a  white  powder  which 
crystallises  from  methylic  alcohol  in  beautiful,  glistening,  prismatio 
needles. 

0-1476  gave  03656  COg  and  0-0954  H^O.     O  =  67-55 ;  H ^ 7-18. 
0-1332     „    0-3311  OOg    „    0-0867  HjO.     0  =  67-79 ;  H«:  7-21. 
CjiHiPg  requires  C«  68-05  ;  H  =  7-22  per  cent. 

Ethoxyparaxylic  acid  melts  at  173 — 174°;  it  is  sparingly  soluble  in 
water  and  light  petroleum^  but  readily  in  ethylie  and  methylic  alcohols, 
benzene,  and  ethylie  acetate. 

COOH 
MethoxymeUiylterejMhalic  Acid,  ^^fPf  Y'^s 

OOOH 

Methoxyparaxylic  acid  is  moderately  readily  acted  on  by  potassium 
permanganate  in  alkaline  solution,  with  formation,  in  the  first  instance, 
of  methoxymethylterephthalic  acid.  In  studying  this  oxidation,  the 
pure  acid  was  dissolved  in  dilute  sodium  carbonate,  heated  to  boiling, 
and  a  strong,  hot  solution  of  potassium  permanganate  added  drop  by 
drop  until  the  colour  remained  permanent  for  some  minutes;  the 


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PERKIN  :  OXIDATION   OF  SULPHOCAMPHYLIC   ACID.  195 

excess  of  permanganate  was  then  destroyed  by  the  addition  of  a  drop 
of  alcohol,  and,,  after  filtration,  the* filtrate  evaporated  to  a  small  bulk 
was  acidified  with  hydrochloric  acid. 

The  bulky,  white  precipitate  which  separated  at  once,  was  collected, 
washed  well,  and  crystallised  from  dilute  alcohol. 

0-1263  gave  02648  CO^  and  0-0570  H^O.  C  =  57-18 ;  H  =  5-01. 
01643  „  0-3223  CX)j  „  0-0679  H^O.  0  =  56-95;  H  =  4-88. 
CH30-CeH,(CH8)(COOH)2  requires  0  =  57-14;  H  =  4-76  per  cent. 

Methozymethylterephthalic  acid,  when  heated  in  a  capillary  tube, 
sinters  at  about  250°,  and  melts  completely  at  267°.  It  is  only 
sparingly  soluble  in  cold  water,  but  crystallises  well  from  large 
quantities  of  boiling  water.  With  ferric  chloride,  the  aqueous  solution 
gives  an  ochreous  precipitate. 


HydroxyTMihylterejihihcilic  Add, 


In  order  to  prepare  this  acid,  methozymethylterephthalic  acid 
(3  grams)  was  boiled  with  fuming  hydriodic  acid  (30  c.c.)  in  a  reflux 
apparatus  for  2  hours.  The  liquid,  which,  on  cooling,  became  filled 
with  crystals,  was  diluted  with  water,  filtered,  and  the  crystals 
washed  with  a  little  dilute  sulphurous  acid  to  remove  iodine.  In  this 
condition,  the  crystals  are  nearly  insoluble  in  water,  but  if  the  solution 
in  dilute  alkali  is  heated  to  boiling  and  acidified,  the  acid  does  not 
separate  at  once,  and  the  filtered  solution,  on  slowly  cooling,  deposits 
a  voluminous  precipitate  consisting  of  microscopic  needles,  The  pre- 
cipitate was  collected,  washed  well,  and  analysed,  with,  the  following 
result. 

0-1512  gave  0-3063  COj  and  00580  HjO.     0  =  55-24 ;  H  =- 4-26. 
OH- CeHj(OHg)(0OOH)2  requires  0  =  55-10.     H  =  408  per  cent. 

Hydroxymethylterephthalic  acid  melts  at  280 — 283°,  and  its  solu- 
tion in  methylic  alcohol  gives,  with  ferric  chloride,  an  intense  reddish- 
violet  coloration. 

OWXNB  COLLEOE, 

Manchester. 


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196        ackroyd:  researches  on  moorland  waters. 

XXIII. — Researches  on  Momiand   Waters.     L  Acidity. 

By  William  Aokeotd,  F.LO. 

Moorland  waters  are  consumed  at  present  by  over  five  and  a  quarter 
millions  of  people  in  Yorkshire,  Lancashire,  Westmoreland,  and 
Cumberland.  Their  well  known  plumbo-solvent  action  has  been  con- 
sidered of  such  importance  as  to  warrant  a  €k}yernment  investigation, 
the  results  of  which  will  be  found  collated  by  Mr.  W.  H.  Power,  F.K.S., 
in  the  Supplement  to  the  Twenty-third  Annual  Beport  of  the  Local 
Government  Board,  pp.  332 — 124,  and  it  is  there  demonstrated  from 
the  work  of  Mr.  and  Mrs.  Atkinson  and  Drs.  Barry  and  A.  C, 
Houston  that  acidity  and  lead  dissolving  power  run  parallel  to  each 
other.  In  common  with  many  analysts,  I  have  long  associated 
plumbo-solvent  power  with  acidity,  and  in  an  investigation  made  for 
the  Halifax  Corporation  concerning  Moorland  waters  from  many 
gathering  grounds,  I  reported  to  this  effect  in  1895.  References  to 
the  question  are  made  in  papers  by  Messrs.  A.  H.  Allen,C.  Rawson,  and 
T.  Whitaker  (Journal  qf  tkt  Society  qfJDyw  and,  Colourieia,  5, 64—71). 
The  question  of  acidity  is  undoubtedly  of  primary  importance  in  con- 
sidering this  class  of  waters,  and  the  following  experiments  and 
observations  thereon  will,  therefore,  be  of  interest. 


Method  of  Estimating  Acidity. 

The  solutions  to  be  dealt  with  may  be  under  or  a  little  over  xxrornr^^ 
of  normal,  and  as  concentration  by  the  usual  methods  is  objectionable, 
I  have  adopted  the  following  course  of  procedure  as  being  both  the 
easiest  and  quickest,  and  the  least  likely  to  introduce  errors. 

To  100  C.C.  of  the  water  in  a  beaker,  1  or  2  drops  of  alcoholic 
solution  of  phenolphthalein  are  added,  and  N/100  alkali  is  run  in 
from  a  burette  until  a  very  slight  pink  tint  is  obtained ;  this  gives  the 
total  acidity.  Through  a  little  more  than  100  a  c.  of  water,  air,  free  from 
carbonic  anhydride,  is  rapidly  aspirated  for  half  an  hour ;  titration  of 
100  c.c.  of  the  water  thus  treated  gives  the  residual  or  organic  acidity, 
the  difference  between  the  first  and  second  titrations  being  the  volatile 
acidity,  and  as  this  is  very  largely,  if  not  entirely,  due  to  carbonic  acid, 
it  may  be  termed  inorganic  acidity.  As  alcoholic  solution  of  phenol- 
phthalein, when  used  as  an  indicator,  is  sometimes  neutralised  by  the 
addition  of  a  little  alkali,  it  is  well  to  mention  here  the  precaution  that 
not  more  than  1  or  2  drops  of  such  a  solution  should  be  used  in  titrating 
moorland  waters,  or  somewhat  discordant  results  may  be  obtained ; 
this  effect  I  have  traced  to  the  acetate  present  in  the  indicator  solvent. 


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I.   ACIDITY. 


197 


Diffusion, 

In  my  earliest  observations  of  waters  taken  from  places  oontiguons 
to  moorlands,  there  was  gradual  decrease  of  acidity  on  keeping  ;  this 
I  was  at  first  at  a  loss  to  account  for,  but  it  was  eventually  put  down 
to  diffusion ;  the  Winchester  quarts  containing  the  waters  were  kept 
in  a  room  where  they  were  freely  exposed  to  sunlight,  and  they  were 
only  opened  as  required  for  purposes  of  analysis.  In  three  of  these 
samples,  A,  B,  and  C,  the  following  percentage  changes  were  observed. 

Acidity. 


Day  of  testing. 

A. 

B. 

C. 

Average. 

Ist 

100 
86 

67 

100 
86 

63 
42 

29 

100 
76 

26 

100 

8th  

86 

10th  

76 

25th  

60 

86th  

42 

62ii<i 

26 

ISlst 

29 

A  was  from  a  private  well  not  far  removed  from  moorland ;  B  was 
from  another  well  of  the  same  kind,  and  C  was  from  a  trench  7  feet  deep 
dug  into  the  side  of  a  moor-oapped  hill  of  Millstone  Grit.* 

It  was  these  results  which  suggested  the  advisability  of  rapid 
aspiration  of  air  free  from  carbonic  anhydride  as  a  necessary  part  of  any 
method  of  estimating  acidity.  As  a  preliminary  trial,  distilled  water 
was  charged  with  carbonic  anhydride ;  100  c.c.  took  60*1  c.c.  of  N/100 
alkali,  but  after  aspiration  for  half  an  hour  only  0*3  c.c.  of  alkali  was 
required  for  neutralisation,  which  was  the  initial  acidity  of  the  distilled 


*  Some  other  analjrtical  data  concerning  these  samples  are  as  follows. 
Parts  per  100,000. 


Total 
solids. 


NaCl. 


Free  NH,, 


Albuminoid 
NH,. 


N  as  nitrites 

and 

nitrates. 


c.c.  of 

N/100  alkali 

required  per 

100  C.C. 


A.. 
B.. 
C. 


18 
63 
10 


8 

6-4 

21 


nil 
0-03 
nil 


0-005 

0-03 

nil 


0-66 
1-2 


11 
10 
7-2 


It  may  also  be  mentioned  that  all  the  waters  referred  to  in  this  paper  are  of 
permanent  hardness  only. 


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198 


AGKBOTD:  RESEARCHES  ON  MOORLAND  WATERS. 


water.  A  sample  of  the  water  C  was  now  sent  for  and  submitted  to 
rapid  aspiration  for  30  minutes.  Its  acidity  was  reduced  to  26  per  cent, 
of  the  original. 

Water  taken  direct  from  moorland  catchwater  or  stream  maj 
exhibit  little  alteration  on  aspiration.  Thus  a  water  from  a  clough 
receiving  its  supply  from  the  adjacent  moorland  showed  no  appreci- 
able alteration  by  diffusion  in  15  days,  neither  was  the  effect  of 
aspiration  any  more  marked.  Some  freshly-collected  samples  from 
very  peaty  gathering  grounds  gave  respectively  14,  11,  5,  and  6  per 
cent,  of  volatile  acidity,  calling  the  total  acidity  100.  The  following 
figures  were  obtained  with  waters  from  moorland  reservoirs. 


Acidity, 
cc,  qf  JV/100  alkali  required  per  100  cc. 


Sample. 

Total. 

Organic. 

Inorganic. 

D 

E.    .. 

Centre  of  large  peaty  reaeiroir 
Small  reseryoir 

6-3 
1-3 
2-9 

4-1 
0-8 
2-0 

1 '2 =22  per  cent. 
0*6=88    ,.     .. 

F 

»»          i>        

0-9  =  81    „     „ 

Configuration  of  Gathering  Grounds. 

Some  of  my  observations  appear  to  throw  a  new  light  on  the 
somewhat  old  problem,  why  one  gathering  ground  should  yield  waters 
which  acted  much  more  quickly  on  lead,  or,  in  other  words,  were  so  much 
more  acid,  than  others.  This  has  been  a  fruitful  subject  of  discussion 
and  of  municipal  inquiry,  in  the  course  of  which  expressions  have  been 
evolved,  and  have  come  into  use  as  synonymous  with  bad  and  good 
waters  as,  for  instance,  **high  "  and  "  low-level  "  supplies,  the  former 
being  regarded  as  productive  of  epidemics  of  plumbism.  I  have  found 
that  mere  altitude  of  gathering  grounds  is  not  sufficient  to  account  for 
some  of  the  striking  differences  observed  in  these  waters.  Certainly, 
one  of  the  worst  waters  with  which  I  have  had  to  deal  is  a  high-level 
one,  the  reservoir  being  1300  feet  above  sea-level,  and  better  waters 
have  been  had  from  reservoirs  860  to  1020  feet  high ;  on  investi- 
gation, however,  it  appeared  that  some  of  the  latter  have  gathering 
grounds  rising  to  a  higher  level  than  in  the  former  case.  The 
**  high  "  and  **  low-level "  distinction  has,  therefore,  seemed  to  me  of 
little  or  no  value,  and  I  have  come  to  the  conclusion  that,  other 
things  being  equal,  it  is  rather  a  question  of  the  average  gradient  of  a 
gathering  ground.  The  reasons  for  this  conclusion  are  that  the 
acidity  lis  due  to  the  peat  through  which  the  water  passes,  and  that 
there  will  be  less  time  for  solution  or  the  taking  up  of  the  acid  wher^ 


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I.  AciDiry. 


199 


the  gradient  is  a  high,  one  than  where  it  ifl  a  low  one.  I  have 
submitted  this  hypothesis  to  the  test  in  a  comparison  of  four 
gathering  grounds  on  like  geological  strata — ^the  Millstone  Grit — with 
the  foUowing  results. 

Gathering  ground. 


Reservoir  or 
clongh. 

^'^\eYdr*"*         ^"^*^°*- 

Total  acidity. 

G 

1880  to  1460  feet                   1  in  44 

6-8 

H 

980  „  1100    „             1  in  28  to  1  in  28 

2-2 

I 

986  „  1480    „        1              1  in  12 
1076  „  1344    „                     1  in  12 

1-4 

J  

10 

Corrdation  qf  Acidity  cmd  Absorbed  Oxygen  Nwmbere. 

Another  fruitful  source  of  speculation  has  been  the  nature  of  the 
acidity  of  moorland  waters.  The  earliest  idea  attributed  it  to 
mineral  acids;  now  it  is  put  down  to  peaty  acids  or,  to  be  more  precise, 
to  humic  acid.  It  appeared  not  unlikely  that  moist  combustion  com- 
bined with  organic  acidity  determinations  might  throw  further  light 
on  the  subject,  as,  for  example,  some  direct  relation  between  the 
absorbed  oxygen  numbers  and  those  for  organic  acidity,  on  the  assump- 
tion that  the  organic  acidity  represents  the  presence  of  a  carbon  com- 
pound of  definite  composition.  Forschammer's  permanganate  process 
was  employed,  the  length  of  the  time  allowed  being  4  hours.  The 
following  observations  are  for  waters  from  widely  different  moorland 
sources. 


Parts  per  100,000. 

Sample. 

Organic 
acidity. 

Absorbed 
oxygen. 

Calculated 
organic 
carbon. 

K 

From  a  large  serrice  reservoir  of  public 
sopply 

0-6 
11 

61 

6-9 

0  021 
0-046 

077 

0-94 

0*050 

L 

K 

AnoUier  supply  of  inferior  quality.... 
From  the  feeder  to  a  reservoir  of  com- 
pensation water;  running 

0108 
1*848 

N 

From  the  same  source  as'k ;  feeder 
f^t^gnant ....x. 

2*256 

0 

Mountain  stream 

1-4    - 

By  inter- 
polation 
Found 

1  0126 
0-16 

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200 


ACRBOYD:   RESEARCHES   ON   MOORLAND  WATERS. 


The  absorbed  oxygen  is  here  converted  into  organic  carbon  by  using 
Sir  E.  Frankland's  factor  2*4.  This  step  was  checked  by  referring 
back  to  his  analysis  of  a  moorland  water,  made  for  official  purposes, 
and  of  which  I  had  a  duplicate  sample,  0.  The  organic  acidity  was 
1*4  ;  this  gives  0*125  part  of  organic  carbon  per  100,000  by  interpo- 
lation, as  against  0*15  part  returned  in  the  analysis. 

The  direct  relation  looked  for  only  appears  in  the  first  two  observa- 
tions. Afterwards,  as  the  acidity  increases  and  the  yellow  colour 
deepens,  the  carbon  appears  to  increase  abnormally,  as  shown  in  curve 
I.  in  the  diagram. 


M    ,*«    >ff   *»  JM    4«    90    9^  »t.  a^    M    «••    iM   41*    W    *'•    ^ 

CAf^BON       Parts    PcR  100000 


The  general  assumption  that  the  acidity  is  due  to  humio  acid  is 
somewhat  wanting  in  precision,  seeing  that  some  half-dozen  humic  acids 
have  been  found  oj  late  years.  The  basicity  of  two  have  been  ascer- 
tained, namely,  Detmer's  octobasic  acid,  C^Q'H^fi^  {W(Ut8'  Dictumaryf 
7,  648),  and  Berthelot  and  Andre's  tribasic  acid,  C^^K^fi^  (Abstr., 
1891,  1089).  The  curve  for  the  carbon  of  the  latter  approaches 
nearest  to  my  observations  for  moorland  waters  (curve  II,  diagram) ; 
yet  it  is  so  far  away  from  it  that  one  is  warranted  in  concluding 
that  the  organic  acidity  of  moorland  waters  is  due  to  an  acid  or 
acids  of  lower  equivalent  than  that  of  the  humic  acids  whose  basicity 
has  been  ascertained  up  to  now. 

The  Bobouoh  Labobatobt, 

Halifax,  Yorkshire. 


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STERN:   THE  NUTRITION   OF  YEAST.      PART  I.  201 

XXIV.— 7%6  Nutrition  of  Yeast.     Part  I. 

By  Arthur  L.  Stern,  D.Sc. 

Solutions  in  which  yeast  grows  freely  and  ferments  yigorously, 
always  contain,  besides  a  fermentable  sugar,  certain  inorganic  salts  and 
nitrogenous  organic  compounds  required  for  the  growth  and  development 
of  the  yeast. 

The  composition  of  yeast  ash  indicates  that  the  inorganic  constituents 
are  chiefly  potassium  and  magnesium  phosphates ;  small  quantities 
of  calcium,  silicon,  sulphur,  and  iron  are  also  usually  present. 
A.  Mayer  (UtUersttohufigen  iiber  die  alko?iolische  GHhrung,  Heidelberg, 
1869),  who  examined  the  nutritive  value  of  a  large  number  of  salts, 
concluded  that  magnesium  and  potassium  phosphates  could  supply  all 
the  inorganic  nutriment  required  by  yeast.  There  is,  however,  con- 
siderable conflict  of  evidence  amongst  later  investigators  as  to  the 
necessity  for  any  other  inorganic  food.  Lintner  (Lehrbtush  der 
Bierhraner,  p.  427)  says  sodium  and  iron  are  not  necessary ;  H.  Molisch 
{Bet.  Cenir^  1894,  167)  says  iron  is  necessary,  but  that  calcium  is  not ; 
Wehmer  {Beitrage  zur  Kentnisa  einheimischer  Filze,  p.  158)  disputes  the 
necessity  for  iron  ;  whilst  Leyffert  (Zeitschr, /v/r  das  gee,  Brau,^  1896, 
318)  states  that  yeast  degenerates  in  the  absence  of  calcium  salts. 

The  necessity  for  sulphur  in  some  form  or  other  is  generally  assumed, 
although  it  does  not  appear  to  have  been  ever  proved. 

Mayer  (loc,  eit)  also  examined  the  nutritive  value  of  a  number  of 
nitrogenous  substances,  and  found  that  the  most  suitable  were  aspara- 
gine,  aUantoin,  carbamide,  and  diffusible  peptones ;  ammonium  salts 
were  not  very  useful ;  colloidal  albuminoids,  like  white  of  egg,  fibrin, 
and  casein,  were  useless,  as  also  were  nitrates.  '  These  deductions  are 
in  general  agreement  with  those  of  later  observers,  amongst  whom 
may  be  mentioned  Matthews  {Jour,  Inat,  Brewing^  1897,  369),  Ehrich 
{Der  Bierbrauer,  1895,  145,  161,  and  177),  and  Wahl  and  Hanke 
{Amer.  Brewers*  ^ev.,  7,  32);  the  latter  state  that  yeast  exerts  a 
selective  influence  on  the  nitrogenous  constituent-s  of  malt  worts, 
assimilating  most  of  the  amides,  and  only  small  portions  of  the  pep- 
tones and  albuminoids. 

Whilst  a  fairly  general  agreement  prevails  that  certain  substances 
aie  necessary  for  the  growth  and  development  of  yeast,  yet  very  little 
is  known  as  to  the  amount  required,  or  of  the  effect  which  a  variation 
of  the  amount  and  proportion  of  these  substances  produces  on  the 
quantity,  composition,  and  properties  of  the  yeast. 

Almost  the  only  work  in  this  direction  is  that  of  Hayduck  {Zeit- 
sehriftfwr  SpirUtisind.,  1881,  173),  who  determined  the  effect  of  vary- 


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202  STERN  :  THE  NUTRITION   OF   YEAST.      PART  I. 

ing  the  amount  of  nitrogenous  nutriment  on  the  weight,  the  amount 
of  nitrogen,  and  the  fermentative  power  of  the  yeast.  He  found  that 
the  amount  of  nitrogen  in  yeast  can  vary  very  considerably,  that  any 
increase  of  nitrogenous  nutriment,  in  the  form  of  asparagine,  up  to 
0*05  gram  nitrogen  per  100  c.c,  results,  not  only  in  an  increase  in 
the  weight  of  yeast,  but  also  in  an  increase  in  the  percentage  of 
nitrogen  present  in  it,  but  any  increase  in  the  nitrogenous  nutriment 
above  that  mentioned  neither  increases  the  weight  of  yeast  nor  the 
percentage  of  nitrogen  in  it. 

Hayduck  determined  the  fermentative  power  of  the  yeasts  obtained 
in  these  experiments,  and  found  that  those  which  contained  the 
highest  percentage  of  nitrogen  had  the  greatest  fermentative  power. 

Kusserow  (Brermerei  £^eitung,  1897,  317)  states  that  the  addition  of 
asparagine  to  a  fermenting  solution  increases  the  rapidity  of  fermenta- 
tion, but  diminishes  the  yield  of  yeast ;  Heinzlemann  (Zeiisehr,  fur 
Spiritu8tnd,f  1897,  296  and  311)  makes  a  similar  statement  with 
regard  to  the  rapidity  of  fermentation. 

The  effect  of  varying  the  amount  of  inorganic  nutriment  has  never 
been  exhaustively  studied,  and  the  statements  made  on  the  point  are 
not  concordant;  Kusserow,  for  instance  {loe,  dt),  found  that  an 
increase  of  inorganic  nutriment  increased  the  rate  of  fermentation, 
the  yield  of  yeast,  and  its  fermentative  power,  whereas  Heinzlemann 
{loc,  cit,)  states  that  it  produces  no  effect  on  the  rate  of  fermentation. 
A.  G.  Salomon  and  W.  de  Y.  Matthews  {Joum,  Soc.  Chem,  Ind,,  1889, 
376)  found  that  the  addition  of  phosphates  to  malt  worts  decreased 
the  assimilation  of  nitrogen  and  phosphorus  by  the  yeast. 

The  experiments  described  in  this  communication  were  undertaken 
with  the  object  of  determining  the  effect  which  the  variation  of  the 
amount  of  inorganic  and  nitrogenous  nutriment  produces  on  the  crop 
of  yeast,  the  assimilation  of  nitrogen,  and  the  fermentation  of  the 
sugar  in  a  given  time. 

Although  some  of  these  problems  have  been  solved  by  Hayduck, 
experiments  of  this  nature,  to  be  strictly  comparable,  must  be  carried 
out  under  absolutely  identical  conditions;  moreover,  they  acquire 
additional  value  when  considered  in  relation  to  similar  work  carried 
out  under  somewhat  different  conditions.  On  this  account,  it  was 
considered  advisable  to  make  the  investigation  as  complete  as  possible. 

Method  qf  £aBperimerU, 

The  experiments  were  made  in  flasks  holding  rather  more  than  a 
litre,  into  which  the  required  amount  of  mineral  and  nitrogenous 
nutriment  was  introduced,  together  with  500  c.c.  of  a  10  per  cent, 
solution  of  pure  dextrose,  and  the  neck  of  the  flask  was  plugged  with 


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8TSRN:  THE  NUTRITION  OF  YEAST.   PART  I.      203 

cotton  wool.  The  solution  was  then  boiled  for  some  minutes  in  order 
to  sterilise  the  contents,  and  when  cold  the  yeast  was  added.  The  flasks 
were  kept  at  a  temperature  of  24°,  and  well  shaken  twice  a  day,  when 
the  odour  of  the  evolved  gases  was  noted. 

At  the  end  of  the  stated  time,  the  yeast  was  filtered  off,  washed 
tmoe  with  cold  water,  dried  at  100°,  and  the  nitrogen  in  it  determined 
by  Kjeldahl's  method.  The  fermented  solution  was  boiled  until  the 
alcohol  was  expelled,  cooled,  made  up  to  its  original  volume,  and  its 
optical  activity  observed,  from  which  the  amount  of  dextrose  remain- 
ing in  solution  could  be  calculated. 

The  yeast  employed  throughout  this  investigation  was  prepared 
from  a  Burton  pitching  yeast.  An  Esmarch  roll  culture  was  made 
with  wort  gelatin,  and  when,  after  incubating,  the  colonies  appeared, 
one  was  introduced  into  a  Pasteur  flask  containing  sterile  hopped 
wort.  Three  such  flasks  were  thus  seeded,  and  from  these  all  the 
yeast  used  in  this  investigation  was  obtained.  Neither  in  their  micro- 
scopic appearance  nor  in  the  flavour  of  the  beer  produced  by  them 
eould  any  difference  in  these  yeasts  be  detected,  and  they  in  no 
appreciable  way  differed  from  normal  Burton  yeast. 

In  order  to  obtain  sufiScient  yeast  for  each  series  of  experiments, 
the  fermented  wort  was  decanted  from  one  of  the  Pasteur  flasks,  which 
was  then  filled  up  with  sterile  hopped  wort,  and  well  mixed  with  the  yeast 
sediment ;  a  portion  was  then  poured  into  a  flask  containing  500  c.c. 
of  sterilised  hopped  wort.  Fermentation  soon  began,  and  when 
finished  the  yeast  fell  to  the  bottom ;  the  fermented  wort  was  then 
poured  off,  and  the  yeast  well  mixed  with  sterilised  water.  The 
number  of  yeast  cells  in  a  measured  volume  of  this  was  counted,  and 
sufilicient  added  to  each  flask  containing  the  solution  to  be  experimented 
on,  to  give  1*5  cells  per  1/4000  cubic  mm. 

Asparagine  was  chosen  as  the  nitrogenous  nutriment,  since  it  is 
easily  obtained  in  a  pure  state,  and  previous  observers  have  found  it 
a  very  suitable  yeast  nutriment.  It  contains  1 8  '7  per  cent,  of  nitrogen. 
The  mineral  nutriment  A  was  prepared  by  dissolving  the  ash  of 
yeast  in  a  weak  aqueous  solution  of  tartaric  acid ;  B  was  prepared  by 
dissolving  potassium  phosphate,  magnesium  sulphate,  and  calcium 
sulphate  in  water. 

A.  B. 

PaUanam  silicate 0'8        Calcium  sulphate 8'2 

Caldnm  hydrogen  phosphate I'd        Magnesium  sulphate    15*9 

Magnesium  hydrogen  phosphate. .  1 0  '5        Potassium  hydrogen  phosphate . . .  80  *9 
Potassium  hydrogen  phosphate... 87 '9 

100-0  1000 


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204  STERN  :   THE  NUTRITION   OF  YEAST.      PART  L 


EXPEBIMBNTAL. 

Four  series  of  experiments  were  made  with  nutriment  A.  In  the 
first  of  these,  0*058  'gram  per  100  c.c.  of  A  was  used,  and  varying 
amounts  of  asparagine  were  added  in  different  experiments.  After 
7  days,  only  about  half  of  the  sugar  was  fermented. 

In  the  second  series,  the  conditions  were  the  same,  except  that  the 
fermentations  were  continued  for  12  days ;  here,  about  three-quarters 
of  the  sugar  were  fermented. 

In  the  third  series  of  experiments,  the  amount  of  inorganic  nutri- 
ment was  doubled,  when  as  much  sugar  was  fermented  in  7  days  as 
was  fermented  in  the  second  series  in  12  days. 

In  the  fourth  series,  three  times  the  original  amount  of  inorganic 
nutriment  was  used,  but  this  had  no  further  effect. 

The  presence  of  a  considerable  amount  of  unfermented  sugar  indi- 
cates the  absence  of  some  essential  yeast  nutriment. 

A  series  of  experiments  were  then  made  with  inorganic  nutriment 
B,  almost  identical  with  that  used  by  Hayduck,  and  chiefly  differing 
from  A  by  the  presence  of  sulphates.  In  these  experiments,  the  sugar 
was  almost  completely  fermented  in  7  days,  whilst  the  amount  of  yeast 
and  of  assimilated  nitrogen  was  much  greater  than  in  the  first  series 
of  experiments. 

As  all  other  conditions  were  identical,  this  must  be  due  to  the 
difference  in  composition  between  nutriments  A  and  B,  and  in  order 
to  determine  if  the  presence  of  sulphates  in  the  one  and  their  absence 
from  the  other  was  the  cause  of  the  difference  in  their  behaviour, 
experiments  were  made  with  nutriment  A  with  the  addition  of 
sulphate,  and  with  nutriment  B  with  its  sulphate  replaced  by  chloride. 
These  experiments  proved  that  the  absence  of  sulphate  was  the  cause 
of  the  difference  observed.  This  question  of  sulphur  nutriment  is  of 
considerable  interest,  and  will  be  treated  fully  in  a  future  paper. 

Nutriment  B  was  used  throughout  the  remainder  of  the  experiments. 

From  comparative  experiments,  it  was  found  that  the  presence  of 
iron  has  no  effect  on  any  of  the  functions  of  yeast  investigated  in  this 
paper,  and  cannot  be  said  to  be  essential  to  the  growth  and  develop- 
ment of  the  yeast. 

When  all  the  elements  necessary  for  the  growth  of  the  yeast  were 
present,  it  was  found  that  the  greatest  amount  of  nitrogen  assimilated 
by  the  yeast  (0*3246  gram)  in  any  experiment  was  0*0227  gram  per 
100  C.C.,  and,  although  in  some  experiments  more  than  six  times  this 
amount  of  nitrogen  was  supplied,  yet  the  yeast  was  never  able  to  assimi* 
late  more  than  the  amount  just  mentioned.  From  experiments  made  by 
Nageli  and  Low  {Zeitaehr./ur  das  gesammte  Brauioesen,  1878,  337)  and 


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STftlLK :  THE  NtJT&ITlON  OF  YEAST?.     tART  L  205 

otherSy  it  has  been  found  that  the  weight  of  the  inorganic  constituents 
of  yeast  is  approzimatelj  equal  to  the  weight  of  the  nitrogen  it  con- 
tains. In  round  numbers^  then,  a  supply  of  0*026  gram  per  100  c.c. 
of  inorganic  nutriment  and  of  nitrogen  as  asparagine  is  as  much  as 
the  yeast  (0*325  gram)  is  able  to  assimilate  under  the  conditions  of 
these  experiments.     This  may  be  called  a  normal  supply. 


A. — Effect  qf  Varying  the  Amotmt  qflfitrogenoiu  Ifutriment  an: 

1.  The  Amount  of  NUrogen  Asaimilctted. — When  the  normal  or  any 
larger  amount  of  inorganic  nutriment  is  present,  any  increase  of 
nitrogenous  nutriment  above  the  normal  has  very  little  effect  on  the 
amount  of  nitrogen  assimilated.  The  experiments  point  rather  to  a 
decrease  of  this  as  the  amount  of  nitrogenous  nutriment  is  increased. 
If  the  amount  of  nitrogenous  nutriment  is  below  the  normal,  the 
assimilation  of  nitrogen  is  much  less  (Expts.  1,  5,  and  6  ;  see  p.  207). 

2.  The  Percentage  qf  NUrogen  AesvmUated. — ^This  is  greatest  when 
the  supply  of  nitrogen  is  least. 

3.  The  Percentage  of  Nitrogen  contained  in  the  Teaet. — ^This  does  not 
vary  when  the  nitrogen  supply  is  normal  or  greater  than  normal ; 
when,  however,  the  nitrogen  supply  is  below  normal,  the  percentage 
of  nitrogen  contained  in  the  yeast  is  low  (Expts.  1,  5,  and  6). 

4.  The  Percentage  qf  Sugar  remaining  Utifermented. — ^This  does  not 
materially  vary,  even  when  the  supply  of  nitrogen  is  below  the  normal ; 
if,  however,  the  inorganic  nutriment  is  present  in  only  normal  amount, 
the  nitrogen  supply  being  below  the  normal  (Expt.  1),  the  amount  of 
sugar  remaining  unfermented  is  large. 

5.  The  Weight  qf  the  Teaet  Crop.— This  is  practically  unaffected 
except  in  the  case  just  noted  (Expt.  1),  when  the  yeast  crop  is  small. 


B. — Effect  of  Varying  the  Amount  qf  Inorganic  Nutriment  on: 

1.  TheAmowtU  of  Nitrogen  Asevm/Uated, — When  the  nitrogen  supply 
is  below  normal  (Expts.  1,  5,  and  6,  p.  207),  an  increase  of  the  inorganic 
nutriment  has  little  effect  on  the  assimilation  of  nitrogen.  When  the 
nitrogen  supply  is  normal  (Expts.  2,  7,  and  8),  an  increase  of  the 
inorganic  nutriment  causes  an  increase  in  the  nitrogen  assimilation. 
When  the  nitrogen  supply  is  above  the  normal  (Expts.  3,  4,  9 — 23), 
little  eff eot  is  produced  by  increasing  the  inorganic  nutriment,  although 
the  trend  of  the  figures  indicates  a  slight  increase  of  nitrogen  assimila- 
tion as  the  inorganic  nutriment  is  increased. 

3.  Hie  Percentage  qf  Nitrogen  contained  in  the  Teaet. — ^When  the 
nitrogenous  nutriment  is  below  the  normal  (Expts.  1,  5,  and  6),  an 

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206  STERN  :  THE  NUTRITION  OF  YEAST.      PART  I. 

increase  of  the  inorganic  nutriment  causes  a  decrease  in  the  percentage 
of  nitrogen  contained  in  the  yeast.  When  the  nitrogenous  nutriment 
is  normal  or  greater,  an  increase  of  the  inorganic  nutriment  has 
practicaUy  no  effect  on  the  percentage  of  nitrogen  in  the  jeast. 

4.  The  PeronUage  qf  Sugtx/r  rtmaining  UnfwmBnUd, — ^When  the 
supply  of  nitrogen  is  below  the  normal  (Expts.  1,  5,  and  6),  an  increase 
of  the  inorganic  nutriment  causes  a  decrease  in  the  amount  of  sugar 
remaining  unfermented.  When  the  nitrogen  supply  is  normal  or 
greater,  an  increase  of  the  inorganic  nutriment  has  little  effect  on  the 
amount  of  sugar  fermented,  although  the  trend  of  the  figures  indicates 
that  this  causes  a  decrease  in  the  amount  of  sugar  remaining 
unfermented. 

5.  Th6  Weight  qf  the  Teast  Crop. — ^This  is  increased  a  little  by 
increasing  the  amount  of  inorganic  nutriment  up  to  0*25  gram,  the 
effect  being  most  marked  when  the  nitrogen  supply  was  least. 

The  results  of  the  experiments  in  which  one  of  the  essential 
elements  (sulphur)  of  yeast  food  is  absent,  present  much  the  same 
genwal  features,  but  the  effect  of  increasing  the  inorganic  nutriment 
is  much  more  marked. 

So  far  as  might  be  expected  considering  the  difference  in  the 
variety  of  the  yeast  used  and  the  differences  in  the  conditions, 
these  experiments  are  in  general  agreement  with  those  of  Hay- 
duck.  It  is,  however,  noteworthy  that,  whilst  Hayduck  found  that 
the  fermentative  power  of  yeast  was  proportional  to  its  nitrogen 
contents,  yet  in  experiments  5  and  6,  in  which  the  proportion  of 
nitrogen  in  the  yeast  was  very  low,  the  fermentation  proceeded  just 
as  far  as  in  the  other  experiments. 

The  most  striking  result  of  this  investigation  may  be  stated  as  an 
enlargement  of  a  proposition  which  Hayduck  deduced  from  his  more 
restricted  work. 

Any  increase  of  nutriment  beyond  a  definite  limit  will  not  materially 
increase  either  the  amount  of  nitrogen  assimilated  by  the  yeast,  the 
percentage  of  nitrogen  or  the  weight  of  the  yeast,  or  the  amount  of 
sugar  fermented.  This  limit  is  but  little  greater  than  the  largest 
amount  which  the  yeast  is  able  to  assimilate  under  the  conditions  of 
the  experiment. 

BiraTON-oN-Twurr, 
October,  1898. 


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STBRK:  THE  KUTIUTION  OP  TSAST.     PABT  L 


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208        SNAPE  AND  BROOKE  :   AN   tROltERtDE  O^  AMARINE. 

XXV. — An  Isomeride  of  Ama/rine. 

By  H.  Llotd  Snape^  D.Sc.y  Ph.D.^  and  Arthur  Bbooks,  PhD. 

AoooBDiNO  to  Laurent  (Armaim,  1844,  62,  366),  benzoylazotide,  on 
distillation,  yields  a  mixture  of  **  amarone  "  and  lophine,  and  we  have 
shown  (Trans.,  1897,  71,  628)  that  amarone  is  tetraphenylazine ;  a 
further  examination  of  the  products  of  distillation  has  shown  that  a 
third  base,  C^iH^g^s'  ^  ^^  present;  this  melts  at  198°,  and  when 
subjected  to  dry  distillation  yields  lophine,  Cj^Hj^N,.  Like  amarine, 
with  which  it  is  isomeric,  it  forms  salts  with  one  equivalent  of  add, 
and  yields  a  mono-silver  derivative,  which,  on  heating,  decomposes, 
with  formation  of  lophine ;  the  silver  derivative  combines  directly  with 
ethylic  iodide,  hence  the  base  contains  an  imido-group. 

The  new  base  differs  from  amarine  in  that  it  has  a  much  higher 
melting  point;  moreover,  its  chromate  does  not  undergo  oxidation 
when  boiled  with  glacial  acetic  acid,  whereas  that  of  amarine  chromate, 
under  similar  conditions,  yields  lophine. 

Neither  is  this  base  identical  with  the  iso-amarine  (melting  at  176°) 
described  by  Feist  and  Arnstein  (Ber.y  1895,  28,  3177),  nor  with  the 
isomeride  of  amarine  (melting  at  269°)  mentioned  by  0.  Fischer 
{Annalen,  1888,  246, 288)  as  having  been  prepared  by  Lorenz  Kohler. 

The  isolation  of  the  base  and  the  preparation  of  some  of  its  deriva- 
tives are  described  below. 

Isolation  of  the  New  Base. 

1.  From  the  Products  of  DistUUUion  qf  Benzoylazotide, — ^The  higher 
distillation  products  of  benzoylazotide,  or  preferably  the  residue  which 
is  left  in  the  retort  when  that  compound  is  heated  to  about  216°,  were 
treated  with  excess  of  warm,  dilute  hydrochloric  acid,  which  diAsolved 
the  base  and  some  resinous  matter,  leaving  the  tetraphenylazine  and 
lophine  undissolved ;  the  base  was  then  precipitated  with  ammonia, 
and  purified  from  resinous  matter  by  suspending  it  in  a  large  quantity 
of  water,  adding  hydrochloric  acid  in  quantity  insufficient  to  dissolve 
the  whole  of  the  base,  and  heating  the  solution  by  passing  in  steam  ; 
the  base  was  then  reprecipitated  by  ammonia.  By  repeating  this 
process  several  times,  the  resinous  matter,  which  is  insoluble  in  pure 
water,  is  gradually  removed,  as  it  remains  adhering  to  the  walls  of 
the  vessel. 

2.  From  Mather  Liquors. — ^The  alcoholic  mother  liquors  obtained  in 
the  preparation  of  benzoylazotide  from  benzaldehyde  and  ammonium 
cyanide  (Trans.,  18971,^71,  629),  especially  when  excess  of  the  aldehyde 

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SNAFE  AND  BROOKE  :  AN   ISOMERIDE  OF  AMABINE.        209 

was  employed^  were  also  found  to  contain  the  new  base ;  the  volatUe 
sabstanoes  were  removed  from  these  liquors  by  heating  with  steam, 
and  the  dried  and  powdered  residue  was  extracted  with  small  quanti* 
ties  of  alcohol  and  ether.  A  crystalline  substance  melting  at  267°  was 
left  behind,  which,  on  analysis,  proved  to  be  lophine,  whilst  the  new 
base  was  extracted  by  dilute  hydrochloric  acid  from  the  residue  left  on 
evaporating  the  alcoholic  ethereal  solution. 

It  was  subsequently  found  that  the  most  convenient  method  for  ex- 
tracting the  base  from  the  benzoylazotide  mother  liquors  consisted  in 
acidifying  with  hydrochloric  acid,  diluting,  and  distilling  with  steam  ; 
the  hydrochloride  of  the  base  was  thus  obtained  in  solution,  whilst  the 
resin,  benzoylazotide,  and  the  hydrochloride  of  lophine  remained  un- 
dissolved. The  last-named  salt  was  isolated  in  octahedral  crystals,  in 
one  experiment,  by  crystallisation  from  chloroform ;  but  generally  the 
residue  was  subjected  to  dry  distillation  at  200 — 215°,  and  the  residue 
left  in  the  distillation  flask  worked  up  in  accordance  with  the  method 
first  given  for  the  isolation  of  the  base.  Most  of  the  base  used  for 
the  experiments  recorded  in  this  paper  was  prepared  by  the  method 
just  described. 

In  all  cases,  the  hydrochloride  was  precipitated  by  ammonia,  and  the 
base  recrystallised  from  alcohol,  when  it  was  obtained  in  colourless 
needles  which  are  soluble  in  benzene  and  chloroform,  and  melt  at  198° 
without  decomposing.  The  alcoholic  solution  does  not  become  lumi- 
nous in  the  dark  after  treatment  with  caustic  potash  (distinction  from 
lophine). 

01778  gave  05500  00,  and  00990  H,0.    0  =  8436 ;  H  =  613. 
01885    „     15-3  C.C.  moist  nitrogen  at  10'5°and  760-1  mm.  N  =  9-70. 
OjaHjgNj  requires  0  =  84*56  ;  H  «  6-04 ;  N  =  940  per  cent. 

2^  HydroekUmde,  OsiH^gN^HOi  +  HgO.— A  solution  of  the  base  in 
warm,  dilute  hydrochloric  acid,  decanted  from  the  amorphous  salt 
which  separated  on  standing,  was  evaporated  in  a  vacuum  over  sul- 
phuric add,  when  the  crystalline  salt  slowly  separated.  It  has  an 
alkaline  reaction,  is  exceedingly  soluble  in  alcohol  and  chloroform, 
very  slightly  in  ether  or  benzene,  and  insoluble  in  carbon  bisulphide. 
It  melts  at  135 — 140°  in  a  capillary  tube,  and,  on  cooling,  solidifies  to 
a  transparent  glass.  The  crystals  were  dried  at  100°  until  their 
weight  was  constant. 

0-209  gave  00854  AgCl.    01  =  1005. 

O^HigNyHCl  +  HjO  requires  01  =  1007. 

The  salt  was  not  changed  by  heating  with  concentrated  hydro- 
chloric acid  in  a  sealed  tube  for  6  hours  at  100°. 
PUuinochhrid^y    (0,iHi3N,)^H,Pt01e.— This     was     prepared     by 


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210        SNAPS   AND  BROOKE:  AN   ISOMERIDE  OF  AUABINE. 

pouring  an  aqueons  solution  of  the  hydrochloride  into  a  solution  of 
platinic  chloride,  the  latter  being  in  excess,  and  the  precipitate 
crystallised  from  rectified  spirit.  The  orange-coloured  crystals  thus 
obtained  begin  to  lose  weight  on  heating  to  220 — 230^,  and  fuse  with 
further  decomposition  at  230 — 240^.  The  platinochloride  is  sparingly 
soluble  in  hot  water,  and  rather  more  soluble  in  boiling  alcohol. 

0-2246  gave  00434  Pt.     Pt=  19-33. 
0-3741     „    0-0726  Pt.    Pt  =  19-40. 

(03iHi8Nj)2,B[2PtClg  requires  Pt  =  19-30  per  cent. 

NUrtUe,  GgiHjgNs^HNOg  +  HgO.— The  base  was  dissolved  in  dilute 
nitric  acid  on  the  water-bath,  and  the  crystalline  crust  which  formed 
on  the  bottom  of  the  vessel,  on  standing,  was  redissolved  in  water ; 
the  white  crystals  which  separated  from  the  neutral  solution  thus 
obtained  had  an  alkaline  reaction,  and  after  drying  in  a  vacuum  over 
sulphuric  acid,  melted  in  a  capillary  tube  at  about  165^ 

0-2040  gave  04992  CO^  and  01058  H^O.    0  =  6673  ;  H  =  5  76. 
0-1807    „     17-4  ac.  moist  nitrogen  at  15°  and  755  mm.     N=  11-2. 
02iB[jL8Nj,HN08  +  HjO  requiresO  =  6646 ;  H  =  5*57;  N  =  1 1  OSper  cent. 

Chramate. — A  solution  of  the  hydrochloride,  precipitated  by  potas- 
sium chromate,  gave  a  yellow  precipitate  which  separated  from  hot 
glacial  acetic  acid  in  well-defined,  yellow  crystals.  The  salt  was  not 
altered  by  heating  it  with  glacial  acetic  acid  for  3  hours  at  150°  in  a 
sealed  tube. 

Silver  Derivative,  OjiHi^NjAg. — Freshly  prepared  silver  oxide  was 
dissolved  in  a  dilute  alcoholic  solution  of  ammonia,  and  a  solution 
of  the  base  in  rectified  spirit  poured  in  in  a  thin  stream,  agitating 
meanwhile.  The  almost  white  compound  which  at  once  separated 
was  dried  at  100° ;  after  being  well  washed  on  the  filter  with  alcohol, 
the  light  grey  powder  thus  obtained  consisted  of  exceedingly  minute, 
transparent  crystals  melting  and  decomposing  at  210°.  It  dissolves 
in  minute  quantity  in  boiling  absolute  alcohol,  but  is  insoluble  in 
ether,  benzene,  and  light  petroleum.  When  heated  with  ethylic 
iodide  in  a  sealed  tube  at  100°,  it  dissolves,  forming  a  clear  solution. 

0-1953  gave  04466  CX), and  00756  HjO.     0 - 6236 ;  H - 4-30. 
0-2503     „     15  o.c.  moist  nitrogen  at  21°  and  764-3  mm.    N= 6-83. 
0-2041     „    0-0540  Ag.    Ag«26-45. 
OjiHi^NgAgrequireeO  =  62-22;  H  -  4-20;  N  =  6-91 ;  Ag  -  26-67per  cent. 

Although  the  relative  proportions  of  base  and  of  ammoniacal  silver 
solution  were  varied  in  different  experiments,  nothing  but  the  mono- 
silver  derivative  could  be  obtained ;  when  excess  of  silver  was  em- 
ployed, the  yield  was  practically  <|uantitativet 


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STUDIES  OF  TH£  TSBPENES  AND  ALLIED  COMPOUNDS.      211 

ConverHon  qf  the  Silver  DerivaUve  wUo  LojAim. — On  heating  this 
silver  oomponnd  to  fusion,  lophine  was  formed,  but  no  hydrogen  or 
other  gas  was  eyolved.  Two  grams  were  heated  in  a  paraffin  bath  to 
210° ;  the  transparent,  yellow  melt,  which  contained  particles  of  silver 
in  sospenaion,  solidified  to  a  hard  mass  on  cooling ;  the  portion  ex- 
tracted by  hot  benzene,  after  being  crystallised  from  alcohol,  deposited 
fine  needles  sparingly  soluble  in  alcohol,  and  melting  at  267°  without 
deoomposition.  The  alcoholic  solution,  on  adding  caustic  potash, 
became  luminous  in  the  dark  when  shaken  with  air.  These  properties 
indicate  that  the  crystals  consisted  of  lophine. 

Destructive  DietiUation  qfthe  Bcue. 

On  heating  the  base  under  diminished  pressure,  decomposition  oc- 
curred below  360°,  ammonia  being  evolved  and  a  small  quantity  of  liquid 
distilling  over,  the  last  portions  of  which  solidified  on  cooling ;  the 
residue  left  in  the  distillation  flask  and  the  solid  distillate  were  dis- 
solved in  boiling  spirit,  from  which  lophine  crystallised  out  in  fine 
.  needles ;  the  later  crystallisations,  which  also  contained  lophine,  were 
digested  with  warm  dilute  hydrochloric  acid,  which  dissolved  the 
unaltered  base.  On  recrystallising  the  insoluble  portion  from  alcohol, 
more  lophine  was  obtained,  and  also  a  small  quantity  of  a  colourless 
substance  which  separated  in  thin  plates  and  melted  at  about  120° ; 
as  it  volatilised  below  the  melting  point  of  lophine,  it  was  easily 
separated  from  the  latter  by  heating  the  mixed  crystals  in  an  air-bath. 
The  crystals  of  lower  melting  and  boiling  point  have  not  been  further 
investigated. 

Ukivbbsitt  Collbob  of  Walis, 
Absbtstwtth. 


XXVI. — Studies  of  the  Terpenes  and  Allied  Compounds. 
Nitrocamphor  and  its  Derivatives.  IV.  Nitro- 
camiphor  as  an  Example  of  Dynamic  Isomerism. 

By  T.  Mabtdi  Lowby,  B.Sc. 

Iv  determining  the  specific  rotatory  power  of  nitrocamphor  dissolved  in 
benzene,  it  was  noticed  that  the  solution  showed  a  considerably  greater 
l»vorotatory  power  when  freshly  prepared  than  after  keeping,  and 
this  was  found  to  be  a  specific  property  of  the  substance ;  thus  a 
specimen  which  had  been  crystallised  four  times  showed  a  change  of 
rotatory  power  from  [  a  ],>  =  -  123°  to  - 104°  in  aJS  per  cent,  solution  in 

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212  LOWRY  :  STUDIES  OF  THE  TEBPENES 

benzene,  whilst  after  four  more  crystallisations  the  limits  were  - 1 24°  and 
—104°.     Similar  changes  of  rotatory  power  are  exhibited  by  ir-bromo- 

nitrocamphor,  OgHijBrcCj^         \   which,   like  nitrocamphor,    con- 

tains  a  secondary  nitro-groap;  bat  no  such  changes  have  been 
observed  in  any  compounds  from  which  either  the  nitro-group  or  the 
hydrogen  atom  adjacent  to  it  has  been  eliminated,  that  is,  the 
phenomenon  is  limited  to  seeandary  nitro-derivatives  of  camphor 
Thus  no  change  of  rotatory  power  is  observed  in  freshly  prepared 

solutions  of  the  aa'*chloronitrocamphor,  CgH^^^jL  ^  the  aa'-bromo- 
nitrocamphors,   CgH^^'OL  ^  the  salts  of  pseudonitrocamphor, 

C8Hh<^6        or  the  anhydride,  C8Hh<^6       O^CgH, 

does  any  change  occur  in  such  compounds  as  a-bromocamphor  or 
a-chlorocamphor,  from  which  the  nitro-group  is  absent.  The 
phenomenon  depends,  therefore,  on  the  presence  of  a  particular  group 
in  the  molecule,  and  must  be  ascribed  to  chemical  rather  than  to 
physical  changes  in  the  solution ;  moreover,  as  these  changes  take 
place  in  all  the  solvents  that  have  been  examined,  they  must 
obviously  be  of  the  nature  of  isomeric  or  polymeric  change,  and  are 
independent  of  any  chemical  interaction  with  the  solvent. 

It  has  already  been  shown  that  the  salts  and  the  anhydride  of  nitro^ 
camphor  are  derived  from  a  pseudo-form  of  the  substance  to  which  the 

formula  OgHi^^TNO  was    assigned   (Trans.,    1898,  73,   997) ; 


IV 


nor 


these  substances  have  a  very  high  dextrorotatory  power,  and  it  is  pro- 
bable that  pseudonitrocamphor  itself  would,  in  like  manner,  be  dextro- 
rotatory. The  changes  of  rotatory  power  which  take  place  in  freshly 
prepared  solutions  of  nitrocamphor  can,  therefore,  be  readily  explained 
on  the  assumption  that  the  levorotatory  normal  form  is  partially 
converted  into  the  dextrorotatory  pseudo-form  of  the  nitro-compound, 
which  must  then  be  regarded  as  isodynamic.  In  the  case  of 
ir^bromonitrocamphor,  both  of  the  isodynamic  forms  are  known  in  the 
free  state,  and,  although  large  differences  of  rotatory  power  occur  in 
the  freshly  prepared  solutions,  ultimately,  a  condition  of  equilibrium  is 
reached  which  is  the  same  for  both. 

Cawe  qf  Jfutarotation  in  the  Sugars. — ^The  spontaneous  changes 
of  specific  rotatory  power  which  take  phice  in  freshly  prepared  solu- 
tions of  nitrocamphor  and  ^bromonitrocamphor  are  very  similar  to 
those  which  have  been  observed  in  aqueous  solutions  of  many  of  the 

Digitized  by  VjOOQIC 


AND  ALLIED  COMPOUNDS.  213 

sagaro  and  of  the  acids  derived  from  them.  The  name  of  birotation 
was  originally  applied  to  the  phenomenon  hj  Dubrunfaut  (Gampt. 
rmd.^  1846y  23^  38)  in  order  to  indicate  that  the  transient  initial 
rotatory  power  of  the  solution  was  twice  as  great  as  that  ultimately 
attained ;  this  is  not  so  except  in  the  case  of  glucose,  consequently 
the  names  of  '*  multirotation  "  and  '  *  paucirotation  "  have  been  intro- 
duced by  Wheeler  and  Tollens  (iinna/«n,  1889,  254,  310)  to  indicate 
that  the  ratio  of  the  two  rotations  is  a  number  greater  or  less  than 
unity.  The  essential  feature  of  the  phenomenon,  however,  is  the 
ehcmge  of  rotatory  power  which  takes  place  in  the  freshly  prepared 
solution,  and  the  term  '  mviaroi<Uwn  *  may,  therefore,  be  used  with 
advantage  to  include  all  those  cases  in  which  such  a  change  occurs 
without  reference  either  to  the  sign  or  to  the  relative  magnitude  of 
the  initial  and  final  rotations. 

The  phenomenon  of  mutarotation  was  first  observed  by  Dubrunfaut 
(JoceU,)  in  an  aqueous  solution  of  glucose,  and  has  since  been  shown  to 
occur  in  aqueous  solutions  of  eight  other  sugars,  and  also  in  the  case 
of  several  of  the  acids  and  lactones  derived  from  them ;  a  full  list  of 
^ese  substances,  together  with  the  limiting  values  of  their  specific 
rotatory  powers,  is  given  in  the  accompanying  Table  I  (p.  214).  The 
changes  of  rotatory  power  which  take  place  on  dissolving  gluconic 
lactone  in  water  were  shown  by  Fischer  to  be  due  to  its  partial  conver- 
sion into  the  acid  in  accordance  with  the  reversible  equation  CqHjo^«  + 
Hfi  ^nQ^^fi^ ]  he,  therefore,  suggested  {Ber.,  1890,  ^  2626) 
thaty  in  the  case  of  the  carbohydrates  also,  the  phenomenon  might  be 
due  to  hydration^  the  aldehyde  or  ketone  being  converted  into  a 
polyhydric  alcohol,  just  as  acetaldehyde  appears  to  form  an  unstable 
hydrate  when  dissolved  in  water;  -  Cflg'CHO  +  HjO  ^  CH8*CH(OB[)2. 
This  suggestion  of  Fischer's  is  that  which  has  usually  been  adopted 
to  explain  the  mutarotation  of  the  sugars.  The  case  of  ir^bromonitro- 
camphor  described  in  this  paper  affords,  however,  a  clear  case  of 
mutarotation  which  is  caused  by  isomeric  change  and  not  by  hydra- 
tion, and  it  therefore  appears  probable  that  the  mutarotation  of  the 
sugars  is  likewise  due  to  isodynamic  change,  and  that  when  the  rotatory 
power  has  reached  its  constant  value  two  dynamic  isomerides  are 
present  in  equilibrium  in  the  solution.  In  the  case  of  glucose  and  of 
lactose,  both  isodynamic  forms  appear  to  have  been  isolated  in  an 
wnhydnma  eanditian  as  a-  and  y-glucose,  and  a-  and  y-lactose ;  and  it 
has  been  shown  that  when  dissolved  in  water  the  two  forms  ulti- 
mately yield  solutions  which  are  similar  in  every  respect,  the  constant 
value  of  the  specific  rotatory  power  being  the  same  for  both,  and 
intermediate  between  the  values  observed  in  the  freshly  prepared 
solutions.  The  data  necessary  to  ascertain  the  structure  of  the 
dynamic  isomerid^  are  not  yet  available,  but  it  may  be  suggested 


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214 


LOWBT  :  STUDIES  OF  THE  TESPENES 


that,  in  the  case  of  glucose,  they  would  probably  be  represented  by 
two  of  the  following  formuln. 

CHjOH 
<[jHOH 
<pHOH 
CHOH 
CHOH 
CHO 


CHjOH 
CHOH 

f    (jJHOH 

9  CHOH 

\CHOH 


The  explanation  of  the  phenomenon  of  matarotation  given  here  is 
essentially  different  from  that  recently  put  forward  by  Trey  (Ztit. 
phytikal.  Chem.,  1895,  18,  193 — 218.  Compare  lippmann,  Ber.,  1896, 
29,  203 — 20t),  who  regards  the  phenomenon  as  due  merely  to  a  change 
of  configuration  in  the  molecule,  and  not  to  a  change  of  structure 
such  as  that  suggested  above.     Moreover,  both  Lippmann  (loe.  cit.\ 


Table  L—Mutarotatary  sugars, 

acids f  and  lactams. 

Substance. 

[«)d 
initial. 

constant. 

Reference. 

a-Glacose  

+  106-2** 

+  62-6 
+  22*6 

+  82-9 

+  66-2 
+  36 

+  119 

-104 

-8-1 

+  78-6 

+  117-6 
+  167 

-112 

+  62-6° 

11 

II 

+  65-2 

II 
II 
II 

+  187 

-92-1 

+  8-6 

+  19-2 

+  80-8 
+  104-6 

-77 

/Parens  and  Tollens,  Ann,,  1890, 
\  267, 164. 

Tanret,  C.R.,  1896, 120, 1060. 

Ibid. 

/3-Glucose  

7-Gluco8e  

a-Lactose  hydrate... 

o-Lacto8e(anhydrou8) 
i3-Lacto8e        „ 
7-Lactoae        „ 

Maltose 

/Pawns  and  Tollens,  Ann.,  1890, 
I  267,  170. 

Tschiiioger,  Ber,,  13, 1917  ;  14, 
r  2121  ;  26,  1466. 

/  Parens  and  Tollens,  Ann,,  1890, 
I  267, 172. 

Ibid.,^,  166. 
/Schnelle    and    Tollens,    Ann., 
\  1892,  271,  60. 

/Parens  and  Tollens,  Ann,,  1890, 
I  267, 176. 

Ibid,,  p.  168. 

Ibid.,  p.  174. 
/Gunther    and    Tollens,    Ann., 
\  1892,  271,  90. 

Fructose 

Rhamnose 

Xylose 

Galactose 

Arabinose. 

Facose 

Rhamnonicacid 

„         lactone.. 
Glnoonic  acid 

-7.70 

-84-8 
-1-7 
+  66-9 
-10-6 
-64-8 

-8-6 

-7-0 

-80-r 

-84-0 
+  12 
+  18-8 
-46-8 
-64-0 

-46-9 

+  17-6 

/Schnelle    and   Tollens,    Ann,, 
\  1892,  271,  68. 

Ibid.,  p.  74. 

Ibid.,  p.  81. 

/Allen  and  Tollens,  Ann,,  1890, 
\  260,  212. 
Ibid. 

„       lactone 

Galactonic  acid 

„         lactone... 

Arabonicacid 

Xvlonic  acid 

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AND  ALLIED  COMPOUNDS.  215 

and  Tanr^t  (Btdl.  Soe.  Chem.,  1896,  [iii],  15,  195)  represent  the 
mntarotation  as  being  due  to  the  campl$U  change  of  an  unstable  into 
a  stable  modification  of  the  sugar,  and  therefore  describe  )3-gluco6e  as 
being  isomeric  with  a-  and  y-glucose;  according  to  the  views  put 
f<Mrward  in  this  paper,  a-  and  y-glucose  and  a-  and  y-lactose  represent 
the  two  iflodynamic  forms  of  the  sugar,  in  a  state  of  greater  or  less 
pmitj,  whilst  j9-glucose,  )3-lactose,  isc,,  do  not  represent  any  new  form 
of  isomerism,  but  are  merely  mixtures  of  the  isodynamic  a-  and 
'^forms.  The  view  that  the  sugars  are  isodynamic  substances  in 
exactly  the  same  sense  as  tr-bromonitrocamphor  and  ethylic  aceto- 
aoetate  appears  to  be  entirely  new,  and  the  relationship  here  observed 
between  mntarotation  and  dynamic  isomerism  may  be  regarded  as  a 
general  one  in  all  cases  in  which  it  can  be  shown  that  there  is  no 
chemical  interaction  with  the  solvent  such  as  that  which  leads  to  the 
hydrolysis  of  lactones  in  aqueous  solution. 

MtUarotatian  of  NUroo(»mphar. 

Ordinary  crystalline  nitrocamphor  melting  at  102^  may  be  regarded 
as  oonsisMng  of  the  normal  form,  its  homogeneity  being  vouched  for 
by  the  constancy  of  its  initial  specific  rotatory  power,  and  by  its  well- 
defined,  crystalline  form.  The  column  headed ''  Initial  Specific  Rotatory 
Power  '*  in  Table  II  represents,  therefore,  the  effect  of  the  different 
solvents  on  the  specific  rotatory  power  of  normal  nitrocamphor.  The 
most  noticeable  feature  in  this  column  is  the  sharp  contrast  which 
exists  between  the  paraffinoid  and  the  benzenoid  series  of  solvents  ; 
with  the  exception  of  carbon  bisulphide,  in  paraffinoid  solvents  the 
initial  specific  rotatory  power  is  in  all  cases  less  than  40%  the  values 
ranging  from  (P  in  formic  acid  to  —  37^  in  ether ;  the  benzenoid 
solvents,  on  the  other  ^hand,  give  much  larger  numbers,  the  values 
ranging  from  -  87^  in  a  20  per  cent,  solution  in  toluene  to  - 124^  in 
a  5  per  cent,  solution  in  benzene.  The  introduction  of  a  side-chain 
into  the  benzene  nucleus  causes  a  decrease  in  the  rotatory  power  of 
the  solutbn ;  thus,  in  the  case  of  ethylic  benzoate,  in  which  the  side- 
chain  and  the  nucleus  are  of  nearly  equal  weight,  a  value  is  obtained, 
[aId^*  -  ^^t  which  is  intermediate  between  those  obtained  in  the  two 
groups  of  solvents.  A  further  point  of  contrast  is  seen  in  the  effect 
of  concentration  on  the  initial  rotatory  power ;  in  solutions  in  chloro- 
farm,  the  values  all  fall  within  a  degree,  but  in  benzene  an  increase 
of  15  per  cent,  in  the  concentration  of  the  solution  causes  a  decrease 
of  24®  in  the  initial  specific  rotatory  power,  and  a  similar  decrease  of 
19®  occurs  in  the  case  of  toluene.  The  differences  between  adjacent 
members  of  a  homologous  series  are  also  much  greater  in  the  case  of 
benzenoid  than  of  paranoid  solvents ;  thus,  ^ere  is  a  change  of 


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216  LOWRY;  STUDIES  OP  THE  TERPENES 

+ 18°  on  passing  from  benzene  to  toluene,  and  a  farther  difference  of 
+  7°  between  toluene  and  xylene,  but  the  difference  between  ethylio 
and  propylic  alcohols  is  only  +  2%  and  acetic  and  propionic  acids  differ 
only  by  «-  2°.  These  points  of  difference  are  not  due  to  the  formation 
of  a  polymeric  modification  of  nitrocamphor  in  the  benzenoid  solvents, 
as  an  increase  of  concentration  would  then  produce  an  increase  of 
specific  rotatory  power  in  the  solution  instead  of  the  decrease  actually 
observed,  and,  moreover,  the  freezing  point  of  the  solution  corre- 
sponds with  a  normal  molecular  weight ;  they  can  be  best  explained 
as  being  due  to  the  influence  of  the  normal  nitro-group  on  the 
benzene  nucleus  leading  perhaps  to  the  production  of  an  unstable 
additive  compound  in  the  solution.  This  view  would  be  in  accordance 
with  the  known  existence  of  compounds  formed  by  the  loose  com- 
bination of  picric  acid  with  various  benzenoid  hydrocarbons,  and 
would  serve  to  explain  the  fact  that  the  anomalous  behaviour  of 
benzene  and  its  homologues  is  most  marked  in  dilute  solutions,  that 
is,  when  the  hydrocarbon  is  present  in  large  excess ;  it  may  also  be 
mentioned  that  jMetMio-ir-bromonitrocamphor  has  the  same  rotatory 
power  in  benzene  and  in  chloroform,  whilst  the  normal  a-bromonitro- 
camphor  exhibits  a  difference  of  32°  in  the  two  solvents.  Reference 
may  be  made  here  to  the  difference  between  the  acids  and  alcohols  of 
the  fatty  series,  which  is  especially  marked  in  the  lower  homologues ; 
thus  formic  acid  and  methylic  alcohol  give  a  difference  of  31°,  which 
falls  to  23°  in  the  case  of  acetic  acid  and  ethylic  alcohol,  and  to  19° 
in  propionic  acid  and  propylic  alcohol,  the  two  series  converging  with 
increasing  molecular  weight  towards  a  value  of  about  - 15°. 

On  passing  into  solution,  normal  nitrocamphor  at  once  begins  to 
change  into  the  pseudo-form,  and  as  the  two  forms  differ  very  widely 
in  rotatory  powers  this  alteration  of  structure  is  accompanied  by  a 
corresponding  change  in  the  rotatory  power  of  the  solution ;  within  a 
few  days  or  hours  from  the  time  of  preparing  the  solution,  the  specific 
rotatory  power  becomes  constant  after  undergoing  a  change  of  from 
10°  to  24°  to  the  right ;  the  magnitude  of  the  change  in  the  different 
solvents  is  given  in  column  5  of  Table  II,  and  is  also  represented 
graphically  in  Fig.  1.  It  has  not  been  found  possible  to  isolate  pseudo- 
nitrocamphor  in  a  pure  state,  and  the  percentage  of  each  form  present 
in  the  state  of  equilibrium  cannot,  therefore,  be  calculated  with  any 
degree  of  accuracy ;  as  an  approximation,  its  specific  rotatory  power 
may  be  assumed  to  be  about  + 180°,  a  figure  which  would  compare 
with  that  of  its  anhydride,  of  which  [a]D»  +187°  in  benzene,  and 
+ 167°  in  chloroform,  and  also  with  that  of  its  ir-bromo-derivative  for 
which  [a]  »  + 189°  (see  also  p.  235),  Taking  this  value  as  the  rota- 
tory power  of  pseudonitrocamphor,  the  percentage  of  this  substance  in 
the  state  of  equilibrium  would  be  about  7  per  cent,  in  both  the 


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AND  ALLIED  COMl»OUNDS. 


217 


paraffinold  and  benzenoid  solvents.  From  the  values  given  in  chloro- 
form eolations,  it  will  be  seen  that  the  percentage  of  the  pseudo-form 
increases  with  the  concentration  of  the  solvent,  the  change  of  rotatory 
power  being  12^,  14%  and  16^  respectively  in  5,  10,  and  20  per  cent. 
aolations. 


iZlL 


-wr 


Ji! 


-€0 


-45°^ :^0 


+  20 


Benzeie  5% 
-»     Bi  mzene 


10% 
zene 
Toluenh   5% 


>     Berzene     20% 


TolukiJe    10% 
Toluene 
ene 


Kfl 


20^(Ji 
5% 


Ethylicben 


vate  6 


— >  Cirbon 
Chloroform 


Etier  5%  h 
Ethylii^  Acetate 
Acetone 


5% 
6^% 


Meth 
Ethyl 
PropifJ 


I  alcoHfil   5% 

5% 

alcohol  5  % 

formic 

Acetic 
Propiohic  i 


-r> 


"TIF 


-I2K> 


-103 


-83 


-60 


.450 


t20 


Fig.  1. — Sbowino  magnitudb  of  Changs  of  Rotatobt  Powbb  of 
nitrooamphob  in  diffbrknt  solybntb. 


VdocUy  qftlte  Isomeric  Change. — In  most  of  the  solvents  examined, 
the  whole  course  of  the  change  of  rotatory  power  has  been  followed, 
and  the  observations  have -been  plotted  in  the  form  of  curves,  such  as 
those  which  are  represented  in  Fig.  2,  where  the  specific  rotatory 

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218 


LOWRY:  STUDIES  OF  THE  TERPENES 


powers  are  plotted  as  ordinates,  whilst  the  absoisssB  represent  the 
time  intervals  from  the  moment  when  the  solvent  was  added  to  the 
nitrocamphor.  The  first  reading  of  the  polariscope  was  usually  made 
within  three  or  four  minutes,  and  observations  were  then  taken  every 
minute  during  the  first  half-hour,  and  subsequently  at  longer  in- 
tervals, until  constant  readings  were  obtained.  The  earlier  part  of 
the  curve  is  somewhat  irregular  as  a  rule,  by  reason  of  temperature 
changes,  and  the  values  of  the  initial  specific  rotatory  power  in 
Table  II,  which  were  obtained  by  ezterpolation,  are,  therefore,  given 


10" 

h5^ 

Ac|0j5]l- 



n** 

^^ 

tthylK    ^e« 

9te(5%f. 

■  t£^) 

10** 

— — —           " 

«0° 

y 

\  ^!^ 

t^;::!^ 

^hoTj?-^ 

SO- 

Houns.- 

1 

2 

3 

4 

Fio.  2. — Cttevbs  showing  Ohakos  op  Rotatory  Power  op  Nitrocajiphor 

WITH  TiMB. 


to  the  nearest  degree,  fractional  parts  of  a  degree  having  been  omitted. 
The  curves  given  in  Fig.  2  are  very  similar  to  those  which  have  been 
plotted  by  Parous  and  Tollens  (Afmalmiy  1890,  257,  160)  for  aqueous 
solutions  of  the  sugars,  and  it  is  shown  under  ir-bromonitrocamphor 
that  the  same  equation  is  applicable  to  both  groups  of  substances. 

Effect  qf  Concentration, — The  isomeric  change  usually  proceeds  most 
rapidly  in  concentrated  solutions;  thus  about  a  week  is  required 
before  equilibrium  is  reached  in  a  5  per  cent,  solution  in  chloroform  or 
benzene  at  ordinary  temperatures,  whilst  a  few  hours  are  sufiScient  in 
a  20  per  cent,  solution.   An  opposite  result  was  obtained  by  Hantzach 


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AND  ALLIED  COMPOUNDS.  219 

and  Schnltze  {Ber.,  1896,  29,  2251)  in  the  case  of  pseudophenyl- 
nitromethane,  but  this  may  be  explained  by  the  fact  that  this  com- 
pound is  bimolecular,  and  a  dilute  solution  would,  therefore,  be  most 
favourable  to  its  conversion  into  the  monomolecular  normal  form. 

^eei  qf  TemperaUure. — ^The  velocity  of  change  is  very  much  in- 
creased by  rise  of  temperature;  a  5  per  cent,  solution  in  benzene, 
which  at  ordinary  temperatures  would  change  slowly  during  two  to 
four  days,  was  found  to  have  reached  a  state  of  equilibrium  after 
it  had  been  warmed  to  50^  for  a  quarter  of  an  hour,  and  then  cooled 
during  an  equal  interval. 

If^kionee  qf  the  Sclveni, — ^The  interval  which  elapses  before  equili- 
brium is  reached  is  shown  for  a  large  number  of  solvents  in  colomn  6 
of  Table  II,  whilst  in  column  8  values  are  given  for  the  period  r  which 
elapses  before  the  change  is  half  completed.  The  solvents  may  be 
divided  into  two  groups.  In  solvents  containing  oxygen,  such  as 
the  alcohols,  adds,  ethers,  and  ethereal  salts,  equilibrium  is  reached 
on  the  average  in  about  four  hours  at  15^  the  actual  periods 
ranging  from  a  quarter  of  an  hour  in  acetone  to  half  a  day  in 
ethylio  benzoate.  The  hydrocarbons  and  compounds  such  as  chloro- 
form and  carbon  bisulphide  are  much  less  active,  and  a  period  of  from 
two  days  to  a  week  or  more  is  required  before  equilibrium  is  reached 
in  these  solvents.  A  similar  result  was  obtained  by  Hantzsch  and 
Schultze  {foe.  ct^.),  who  found  that  peeudophenylnitromethane  changed 
more  slowly  in  chloroform  and  in  benzene  than  in  ether,  alcohol, 
water,  or  acetic  acid. 

LaiiU  SohUianB, — From  certain  observations  that  have  been  made 
with  chloroform  solutions,  it  seems  doubtful  whether  the  second  group 
of  solvents  are  capable  by  themselves  of  bringing  about  the  isomeric 
change  at  all.  Out  of  five  10  per  cent,  solutions  that  have  been 
examined,  three  have  been  found  to  persist  during  several  days  in  a 
labile  state  without  undergoing  change,  and  the  same  result  has  also 
been  noticed  once  in  a  5  per  cent,  solution,  but  nothing  of  the  kind 
has  been  observed  in  other  solvents.  Usually,  the  transference  of  the 
solution  to  the  polarimeter  tube  has  proved  sufficient  to  start  the 
change,  but  in  two  teases  the  labile  state  was  found  still  to  persist  • 
however,  the  change  began  on  warming  or  shaking  the  tube.  Two 
coirves  are  given  in  Fig.  3  (p.  220)  to  illustrate  this ;  the  first  curve  re- 
presents the  observations  made  with  a  10  per  cent,  solution,  which 
showed  an  almost  constant  rotatory  power  during  six  days,  until  the 
labile  state  was  destroyed  by  warming  the  tube ;  the  second  curve 
shows  the  behaviour  of  a  5  per  cent,  solution,  one  portion  of  which 
was  transferred  to  the  observation  tube  immediately  after  it  had  been 
prepared,  whilst  the  second  portion  was  not  transfer^red  until  16  days 
later  ;  the  initial  rotatory  power  was  approximately  the  same  in  both 

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220 


LOWRY:  STtJDifiS  Of  THfi  T£ftl»EKES 


cases,  indicating  that  the  solution  did  not  undergo  any  isomeric 
change  while  in  the  iBask,  but  started  at  once  when  poured  into 
the  tube.  The  dotted  line  in  Fig.  3  (a)  shows  the  normal  rate 
of  change  in  a  20  per  cent,  solution  in  chloroform.  From  these 
observations,  it  appears  probable  that  a  solution  of  pure  nitro. 
camphor    in  pure  chloroform    might    be  kept  indefinitely  without 


-10' 


30' 


o                     ^r 

CHLOROFORM 

s% 

t^ 

/ 

/ 

L. - 

5                     1 

0                       1 

5 

Fio.  8.— Labile  Solutionb  in  Chlorofobm  (a)  10  pbr  gent.,  (5)  6  pxb  obnt. 


undergoing  change;  in  practice,  the  solution  slowly  decomposes 
and  assumes  a  yellow  colour,  but  that  even  this  decomposition  does 
not  necessarily  involve  isomeric  change  follows  from  the  fact  that 
a  portion  of  one  of  the  10  per  cent,  solutions  referred  to  was  kept 
during  63  days  in  the  graduated  flask  in  which  it  had  been  prepared, 
and,  although  it  had  a  marked  yellow  colour,  its  rotatory  power  had 
only  fallen  from  -  27"^  to  -  22^  instead  of  the  limiting  value  -  IS"".  . 


Digitized  by  VjOOQIC 


AMD  ALLIED  COMPOUNDS.  221 

These  observations  clearly  indicate  that,  at  least  under  certain  con- 
ditions, a  third  substance  is  necessary  to  bring  about  isomeric 
change  in  the  case  of  nitrocamphor  j  the  results  described  in  the 
following  paragraphs  serve  to  suggest  that  a  trace  of  basic  impurity 
is,  perhaps,  essential  as  a  catalytic  agent ;  as  an  alternative  hypothesis, 
it  might  be  supposed  that  a  trace  of  the  pseudo-form  is  necessary  to 
start  the  action  ;  in  either  case,  there  is  an  interesting  analogy  to  the 
well-known  influence  of  minute  traces  of  water  in  con^tioning 
chemical  change. 

Influence  qfBtues,  Acids,  and  Salts. — ^It  has  been  shown  by  O'Sullivan 
and  Tompson  (Trans.,  1890,  67,  920)  that  the  addition  of  alkali 
causes  the  change  of  rotatory  power  of  the  sugars  to  take  place 
instantaneously  ;  similar  effects  are  produced  in  the  case  of  nitro- 
camphor,  as  may  be  seen  from  the  following  experiments.  A 
quantity  of  nitrocamphor  was  dissolved  in  chloroform  containing 
about  0*5  gram  of  piperidine  per  litre ;  seven  minutes  after  preparing 
the  solution,  the  speciflc  rotatory  power  was  [ajo  =  -  9^,  and  no  marked 
change  of  rotatory  power  was  subsequently  observed ;  the  constant 
rotatory  power,  so  rapidly  reached  in  this  case,  differs  from  that 
previously  given  in  a  5  per  cent,  solution  in  chloroform  only  to  an 
extent  which  is  readily  accounted  for  by  the  partial  conversion  of  the 
nitrocamphor  into  piperidine  salt.  A  similar  result  was  obtained 
when  nitrocamphor  was  dissolved  in  absolute  alcohol  in  which  sodium 
had  been  previously  dissolved  to  the  extent  of  0*25  gram  per  litre ;  in 
this  case,  the  constant  rotatory  power  had  been  reached  when  the  first 
reading  of  the  polariscope  was  taken  three  minutes  after  preparing  the 
solution.  In  another  experiment,  however,  in  which  the  quantity  of 
sodium  was  reduced  to  about  15  milligrams  per  litre,  a  very  rapid 
change  of  rotatory  power  was  observed  at  first,  and  a  constant  value 
was  reached  within  12  minutes  from  the  time  when  the  solution  was 
prepared ;  the  quantity  of  sodium  present  in  this  experiment  was  too 
small  to  produce  any  noticeable  effect  on  the  constant  rotatory  power 
of  the  solution,  which  was  found  to  be  [ajo"  —9^,  the  normal  value 
in  a  5  per  cent,  solution  in  alcohol.  No  effect  of  this  kind  is  produced 
by  aeiis  \  the  addition  of  3*5  grams  of  concentrated  hydrochloric  acid 
per  litre  did  not  cause  any  increase  in  the  velocity  of  change  of  a 
5  per  cent,  solution  of  nitrocamphor  in  alcohol.  Neutral  salts  act 
similarly  to  free  bases,  but  less  strongly ;  the  addition  of  0*7  gram 
of  sodium  chloride  per  litre  to  a  5  per  cent,  solution  of  nitrocamphor 
in  alcohol  was  found  to  reduce  the  period  of  change  from  5  hours 
to  less  than  an  hour. 

The  '  catalytic '  influence  of  bases  can  be  satisfactorily  explained  by 

equations    such    as    the    following,      ^^x^^^^^    ^  +  NaOEt^ 
VOL.  LXXV.  Q 

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222 


lowry:  stxtdies  of  the  xerpenes 


C8Hh<^6         +H0Et^C3H,^<^i 


+  NaOEt.     In   these 


equations,  the  sodium  salt  is  represented  as  being  partially  converted 
by  the  alcohol  into  sodium  ethoxide  and  nitrocamphor,  on  the  one 
hand,  and,  on  the  other,  into  pseudonitrocamphor  and  sodium  ethoxide ; 
these  changes,  which,  of  ^'course,  would  be  incomplete  and  reversible, 
might  be  expected  to  take  place  with  much  greater  velocity  than  the 
simple  isomeric  change,  and  it  may  even  be  questioned  whether  the 
latter  is  capable  of  taking  place  at  all  apart  from  such  '  catalytic 
agents.'  The  interactions  which  are  here  assumed  to  occur  in  an 
alcoholic  solution  of  nitrocamphor  are  strictly  analogous  to  the  hydro- 
lysis of  a  salt  into  its  acid  and  base,  which  is  most  marked  in  dilute 
aqueous  solution,  and  when  either  acid  or  base  is  feeble,  for  example, 
KCN  +  HjO^KOH  +  HON.  Similar  equations  may  be  used  to  explain 
the  action  of  the  nitrogen  bases,  but  here  the  change  would  be  analogous 
to  the  dissociation  of  ammonium  chloride  in  the  gaseous  state,  or  of 
aniline  acetate  in  solution  in  benzene.  The  influence  of  neutral  salts 
may  be  explained  as  dependent  on  the  *  ratio  of  distribution '  of  the 
base  between  the  nitrocamphor  and  the  acid  of  the  neutral  salt.  It  is 
important  to  notice  that  these  catalytic  agents  do  not  disturb  the 

Table  IL — MutaroUriton  of  nitrocamphor. 


'   Specific  rotatory  power, 

Con- 

1 

[«]d. 

Tem- 

Solvent. 

centra- 

Period. 

pera- 

T. 

k,  +  k^ 

tion. 

InitiaL 

1 

Final. 

Diff. 

ture. 

Denzene  

67o 
10 
20 

5 
10 
20 

5 

5 

-124° 

-104'' 

20** 

4  days 

15** 

:    -116 

!  -100 

!    -106 

-100 

-87 

-99 

-50 

-98 
-77 
-87 
-79 
-66 
-75 
-28 

23 
23 
19 
21 
21 
24 
22 

4  days 

iday 

iday 

iday 

iday 

4  days 

iday 

16 
13 
20 
18 
17 
20 
17 

26      h. 

1-8  h. 

4-7  h. 

4-5  h. 

41   h. 
23      h. 

4  1   h. 

0*033 

0*63 

Toluene 

0-17 

018 

0*20 

Xylene 

0-036 

Ethvlic  benzoate.. 

0  20 

Carbon  bisulphide 

5 

-88 

-68 

16 

2  days 

17 

6-9   h. 

012 

Chloroform 

5 
10 
20 

5 

-27 
-27 
-27 
-37 

-15 
-13 
-11 
-18 

12 
14 
16 
19 

Iweek 

1  week 
6  hours 

2  hours 

13 
16 
16 

18 

32      h. 
48      h. 

1-9   h. 

0-83h. 

0-026 

0-017 

0-43 

Ether , 

2-4 

Ethylic  acetate  ... 

5 

-13 

-2 

11 

2  honrs 

14 

0-2   h. 

4  1 

Acetone  

5 

-7 

+  8 

15 

i  hour 

20 

0-06  h. 

16-2 

Methylic  alcohol.. 

5 

-81 

-12 

19 

3  hours 

16 

0-6  h. 

1-6 

Ethylic        „ 

5 

-26 

-9 

17 

5  hours 

15 

1-1   h. 

0-74 

Propylic      „ 

5 

-24 

-10 

14 

2  hours 

17 

0-6  h. 

1-6 

Formic    acid 

5 

±0 

+  12 

12 

3  hours 

15 

0-7  h. 

1*2 

Acetic       ,,     

5 

-3 

+  8 

11 

5  hours 

13 

10  h. 

0-81 

Propionic,,     

5 

-5 

+  5 

10 

2  hours 

14 

0-3  h. 

2-7 

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AND  ALLIED  COMPOUNDS.  223 

equilibriom  between  the  isodynamic  fonxui  of  nitrooamphor,  as  it  has 
recently  been  asstuned  by  Sohiff  that  agents  of  this  kind  are  capable 
of  effecting  the  complete  conversion  of  ethylic  acetoaoetate  into  one  or 
other  of  its  isodynamic  forms ;  this  point  will  be  referred  to  again 
later. 

MiUaraUUion  qf  wBromonitroeamphor. 

Through  the  kindness  of  Dr.  Slipping  in  providing  me  with  the 
necessary  material,  I  have  been  enabled  to  extend  the  investigation  of 
nitrocamphor  by  studying  its  tr-bromo-derivativei  The  introduction  of 
the  bromine  atom  does  not  produce  any  great  difference  in  chemical 
properties,  but  completely  alters  the  physical  properties  of  the  sub- 
stance,  the  most  important  result  being  that  the  pseudo-form  is 
rendered  much  less  soluble  and  can  readily  be  isolated,  whilst  it  is  still 
possible  to  isolate  the  normal  form.  The  condition  of  equilibrium  can, 
therefore,  be  approached  from  either  side,  and  as  the  rotatory  power  of 
the  two  forms  can  be  determined,  the  exact  percentage  of  each  when 
equilibrium  is  reached  can  be  ascertained. 

v-Bromonitrocamphor  was  prepared  and  examined  by  Lapworth  and 
Sapping  (Trans.,  1896,  09,  304),  and  was  described  by  them  as  being 
trimorphous,  the  three  modifications  melting  at  108°,  126°,  and  142°. 
Two  of  these  forms  were  submitted  to  crystallographic  measurement,  and 
the  axial  ratios  and  the  drawings  of  the  crystals  are  given  in  the  paper 
referred  to.  From  the  results  obtained  in  studying  nitrocamphor,  it 
appeared  to  be  possible  that  the  three  crystalline  modifications 
might  include  the  normal  and  pseudo-forms  of  the  substance,  and  they 
were,  therefore,  submitted  to  polarimetric  investigation  in  order  to 
ascertain  the  nature  and  magnitude  of  any  changes  which  might  take 
place  after  dissolving  them. 

The  orthorhombic  form,  melting  at  142°,  is  readily  obtained  in  good 
crystals  from  solution  in  chloroform ;  when  it  is  dissolved  in  benzene,  the 
value  of  [a]i>  changes  from  + 188°  to  -  38°  in  a  3*33  per  cent,  solution  at 
13° ;  in  a  5  per  cent,  solution  in  chloroform  at  14°  the  limits  were  + 189° 
to  +  31° ;  the  magnitude  of  the  change  is,  therefore,  very  large,  being 
two  or  three  times  as  great  as  that  recorded  in  any  previous 
case.  The  high  dextrorotatory  power  of  this  modification  indicates 
that  it  is  the  ptetulo-iormf  whilst  its  purity  is  vouched  for  by  its  definite 
crystalline  form,  since  the  isodynamic  forms  are  not  isomorphous. 
That  the  salts  are  derived  from  this  modification  of  the  substance  is 
shown  by  their  similar  dextrorotatory  power,  that  of  the  hydrated 
potassium  salt,  CioHjgBrNOjK  +  2H2O,  being  [aj^  -  +  221°  in  a  3  per 
cent,  aqueous  solution  at  15°. 

The  tetragonal  form,  melting  at  108°,  is  difficult  to  isolate  in  any 
quantity,  as  it  does  not  begin  to  separate  until  after  the  ortho- 

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224  LOWRY  :   STUDIES  OF  THE  TERPEN ES 

rhombic  form,  when  the  solution  in  chloroform  is  allowed  to  evaporate, 
but  the  crystals  can  be  readily  distinguished  and  picked  out  mechanic- 
ally. When  dissolved  in  benzene,  this  modification  shows  a  change  of 
rotatory  power  from  -  61^  to  -  38°  in  a  3*33  per  cent,  solution  at  15° ; 
it,  therefore,  resembles  nitrocamphor  both  in  the  magnitude  and  in 
the  direction  of  the  change  and  must  be  regarded  as  the  normal  form 
of  the  substance. 

The  third  modification,  melting  at  126°,  separates  from  a  hot  solution 
in  spirit  as  a  crystalline  powder ;  when  dissolved  in  beozene,  a  specimen 
of  this  form  showed  a  specific  rotatory  power  changing  from  + 150°  to 
—  39°,  and  it  must,  therefore,  be  regarded  as  a  mere  mixture  of  the 
normal  and  pseudo-forms  similar  to  that  which  is  obtained  on  allowing 
a  solution  in  chloroform  to  evaporate  to  dryness.  Similar  mixtures 
are  almost  always  obtained  when  crystallisation  takes  place  rapidly, 
and  it  is  only  by  obtaining  the  substance  in  well-defined  crystals 
that  the  purity  of  the  two  forms  can  be  ensured. 

When  brought  into  contact  with  a  solvent,  the  different  modifica- 
tions of  ir-bromonitrocamphor  yield  solutions  which  are  ultimately 
identical ;  in  each  case,  the  same  constant  rotatory  power,  [ajp  »  -  38°, 
is  reached ;  this  affords  a  proof  that  the  equilibrium  is  the  same  in 
each  case  and  corresponds  to  a  mixture  of  1  part  of  the  pseudo-form 
with  17  parts  of  the  normal.  The  production  of  such  an  equilibrium 
has  already  been  indicated  in  connection  with  the  different  modifica- 
tions of  glucose  and  of  lactose,  and  also,  somewhat  imperfectly,  in 
connection  with  the  acids  and  lactones  referred  to  in  Table  I.  The 
changes  of  rotatory  power  of  normal  and  pseudo  ?r-bromonitrocamphor 
in  solution  in  benzene  are  represented  graphically  in  Fig.  4. 

Normal  and  pseudo-ir-bromonitrocamphor  differ  widely  in  physical 
properties ;  they  crystallise  in  different  systems,  their  melting  points 
differ  by  34°,  and  the  specific  rotatory  powers  by  239°  ;  the  difference 
in  solubility  is  also  very  marked,  for  whilst  the  normal  form  dissolves 
instantly  in  cold  chloroform,  the  pseudo-form  only  dissolves  slowly  on 
boiling.  In  general,  the  normal  form  shows  a  behaviour  which 
indicates  a  less  solid  cohesion ;  thus  it  has  a  lower  melting  point  and 
a  greater  solubility  and  is  much  softer  than  the  pseudo-form. 

Form  qf  the  Muta/roiation  Curves, — ^The  change  of  A^bromonitrocam- 
phor  from  the  normal  to  the  pseudo-form,  or  viee  verad,  is  a  mono- 
molecular  action,  and  might,  therefore,  be  expected  to  proceed 
according  to  an  equation  of  the  type 

dx/dt  =  ki{xQ  -  Xt)  -  k^ 

^l^ich,  when  integrated,  becomes 

*,+*,-!  log  5^, 


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AND  ALLIED  COMPOUNDS. 


225 


where  k^,  k^  are  the  velocity-constants  of  the  isomeric  change  in  the 
two  directidns,  and  x^,  xt,  and  «qo  are  the  quantities  of  one  of  the 
forms  at  times  0,  t,  and  oo  .  This  equation  has  already  been  applied 
by  Kiister  to  the  isomeric  change  of  the  two  hexachloroketocyclo- 


-♦-36UU- 

+  160- 

1 

1 

T  lUW 

\ 

+60 

0- 

\tft 

vo 

tlor*SiL^ 

t^ 

-50- 

Z 

3.  DAYS 

Fio.  4. — Changes  or  Rotatort  Power  of  Psbudo-  and  Normal 
v-BROMomTRooAMPHOR  IN  Bbkzenb  (8*88  per  cent.). 

pentenes  {Zeit.  phynkal.  Chem,,  1895,  18,  171),  and  by  Trey  to  the 
mutarotation  of  the  sugars  {ibid,,  p.  198).  In  the  case  of  nitro- 
camphor  and  ir-bromonitrocamphor,  the  most  convenient  unit  of 
measurement  is  that  given  by  the  specific  rotatory  power  of  the 

„.gitized  by  Google 


226 


LOWRY:  STUDIES  OF  THE  TERPENES 


solution^  and  if  oq  be  used  to  represent  the  rotator j  power  of  the 
solution  when  first  prepared,  at  that  at  time  t,  and  a^^  the  constant 
value  of  the  rotatory  power,  then  the  equation  maj  be  written 

-(^  +  *2)  =  7  {log  (ao-aoo)-log  (a«-aoo)  j  , 

where  c  represents  the  base  of  the  natural  system  of  logarithms,  and 
has  the  valtie  2 '7183,  whilst  k^  and  A^  are  the  velocity-constants  of 
the  isomeric  changes  in  the  two  directions,  and  represent  the  pro- 
portion of  each  that  undergoes  isomeric  change  in  the  course  of  one 

hour.     In  Table  III,  the  values  of  the  constant  ^      ^  in  the  case  of 


Tablb  m. — Showing  change  of  rotatory  power  of  peeudo^-hroTnonUro- 
cam/pkoT  in  a  5  per  cent,  solution  in  chloroform  at  14^. 


at  -  tt^. 

t  (hours). 

at. 

*!  +  *« 

f 

Observed. 

Calculated. 

Diiference. 

0     h. 

157-8' 

0-2  h. 

+  188-5' 

157-2' 

156-4 

-0-8' 

0-0080 

0-6  h. 

187-8 

156-0 

154-8 

-1-7 

0-0166 

10  h. 

188-8 

152-0 

150-8 

-1-2 

00163 

8-0  h. 

169-0 

187-7 

137-7 

+00 

0-0197 

6-0  h. 

156-0 

125-7 

125-7 

±0-0 

0-0198 

7-0  h. 

146-0 

114-7 

114-9 

+0-2 

0-0198 

24     h. 

84-5 

58-2 

58-2 

±0-0 

0-0197 

72     K 

87-8 

6  0 

6-0 

±0-0 

0-0197 

81     h. 

86-8 

4-5 

4-0 

-0-5 

0-0191 

96     h. 

84  0 

2-7 

8-2 

+0-6 

00184 

Limit  168  h. 

81-8 

0 

0 

0 

^ 

0-0197 

Mean  value 

a  5  per  cent,  solution  of  pseudo-Tr-bromonitrocamphor  in  chloroform 
are  given  in  the  sixth  column,  and  their  constancy  shows  that,  after 
the  first  hour,  the  change  proceeds  quite  regularly  according  to  the 
monomolecular  law;  the  values  given  in  the  fourth  column  for 
at  -  a^Q  are  calculated  from  the  equation 

log  (at  -  aoo  )  =  0-1981  - 1  x  0-0197, 

and  show  a  very  satisfactory  agreement  with  the  observed  rotations, 
the  difEerences  in  each  case  being  less  than  2°.  In  Table  lY,  values 
are  given  for  both  the  normal  and  pseudo-forms  of  «-bromonitrocamphor 


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AND  ALLIED  COMPOUNDS. 


227 


Table  IV. — Showvng  ckomgt  qf  roUxUyry  power  of  pemtdo-  cmd  normal 
ir-bromonitroccMnphor  in  a  3 '33  per  cent.  soltUion  in  benzene. 


t  (hoara). 

«< 

a«  -  a«. 

(^•i+Ai)*. 

(corr.). 

Temperature. 

0    h. 

(  +  188-4'0 

(220  ^^ 

^^ 



16'C. 

0-6  h. 

-1- 184-0 

2220 

0-0170 

— 

1-0  h. 

+  1797 

2177 

0-0170 

— 

1-6  h. 

+  176-0 

218-0 

0-0173 

— 

8-5  h. 

+  168-2 

196-2 

0-0178 

00216 

6-0  h. 

+  146-2 

188*2 

0-0184 

0-0210 

7-0  h. 

+  129-6 

167-6 

0-0187 

00207 

8-7  li. 

+  116-0 

164  0 

0-0192 

0-0207 

27-0  h. 

+26-7 

687 

0-0204 

00207 

29  0  h. 

+  18-7 

667 

0-0207 

0  0210 

81 -711. 

+  10-7 

487 

0-0210 

0-0212 

48*6  h. 

-17-6 

20-6 

0-0216 

0-0214 

14* 

Limit  99-3  h. 

-88-0 

0 

— 

— 

13' 

0-0188 

0-0210 

Mean  value 

Mean  valae 

Oh. 

(-61-4-) 

(18-9*) 

_ 

13' 

Ih. 

-60-7 

18-2 

— 

25  h. 

^47-2 

97 

0-0062 

48  h. 

-487 

6-2 

0-0078 

72  h. 

-427 

6-2 

0-0069 

118  h. 

-40-0 

2-6 

0-0063 

16' 

Limit  144  1l 

-87-6 

0 

— 

0-0064 

Mean  valae 

in  a  3*33  per  cent,  solution  in  benzene ;  in  the  case  of  the  pseudo-fomii 
the  Telodty-oonstant  ^     ^  in  column  4  shows  a  steady  increase  as 

the  action  proceeds,  but  this  is  due  almost  entirely  to  the  slowness 
of  the  isomeric  change  during  the  first  hour  or  two,  and  the  later  part 
of  the  curve  gives  a  satisfactory  agreement,  as  is  seen  from  the 
constancy  of  the  numbers  given   in  the  fifth  column,   which  are 

calculated  from  the  formula  ^L±^  =  -  /  03700  -  log  (ac  -  aoo  )  | .  Un- 
der comparable  conditions,  the  velocity-constant  ^     ^  should  be  the 

same  for  both  modifications  of  a  substance,  but  it  is  only  rarely  that 
this  agreement  can  be  realised  experimentally ;  in  Table  lY ,  the  mean 

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228  LOWRY  :  STUDIES  OF  THE  TERPBKE8 

value  0*0188,  in  the  case  of  the  pseudo-form,  is  three  times  as  great  as  the 
valuoi  0*0064,  obtained  in  the  case  of  the  normal  form  ;  this  difference 
maj  be  accounted  for  in  part  bj  the  difference  of  2°  in  temperature  in 
the  two  experiments,  but  it  is  probable  that  some  other  points  of 
divergence  existed  between  the  conditions  in  the  two  experiments. 

If  0*0188  be  taken  as  a  mean  value  for  Vt^  then  Jfci+ifej  =  00511, 

and  since  Ajj  rAij- 226*4: 13*9,  *i  =  0*0481  and  Aig^  0*0030,  where  k^  is 
the  velocity-constant  of  the  change  from  pseudo-  to  normal,  and  k^ 
that  of  the  change  from  normal  to  pseudo- ;  thus,  under  the  conditions 
of  the  experiment,  4*8  per  cent,  of  the  quantity  of  the  pseudo-form 
present  in  the  solution  would  undergo  isomeric  change  in  one  hour, 
and  only  0*30  per  cent,  of  the  normal  form. 

In  the  case  of  nitrocamphor,  the  changes  of  rotatory  power  are  too 
small  to  give  a  good  result  on  calculating  the  velocity-constant  from 
the  separate  observations,  but  in  Table  II  the  period  r  which  elapses 
before  the  change  is  half-completed  is  given  in  column  8,  and  from 
this  the  constant  k^  +  k^  has  been  calculated  for  each  solvent  from  the 

formula  kj^  +  k^--  log  |. 


Campariaon  with  the  NUropairaffina. 

It  was,  I  believe,  first  suggested  by  Dr.  Armstrong  in  the  year 
1892  (Proc.,  1892,  101),  that  the  salts  of  the  nitroparaffins  are  derived 
from 'a  hydroxylic  modification  of  the  substance,  and  not  directly 
from  the  nitro-compound.  This  suggestion  was  verified  shortly  after- 
wards by  the  experimental  work  of  Nef  {Annalen^  1894,  280,  263  ; 
Ber.f  1896,  29,  1218),  and  since  then  a  number  of  attempts  have 
been  made  to  isolate  the  hydroxylic  form  of  various  nitroparaffins. 
Labile  crystalline  modificationsof  phenylnitromethane,  C^H^'  CHg*  NOj, 
and  parabromophenylnitromethane,  C^H^Br'CHj'NOj,  have  been 
prepared  by  Hantzsch  and  Schultze  {Ber.,  1896,29,  699  and  2256)  by 
acidifying  an  aqueous  solution  of  the  sodium  salt  with  mineral  acids, 
and  the  same  method  has  been  successfully  used  by  Konowaloff  in  the 
case  of  iD-nitromesitylene,  C^HgMeg'OHj'NOj,  diphenylnitromethane, 

g«^»>CH-NOj,  isopropylphenylnitromethane,  q«2''>CH-N0„   and 

other  secondary  nitroparaffins  {Ber.^  1896,  29,  2193).  These  labile 
forms  appear  to  consist  largely  of  the  dynamic  isomeride  from  which 
the  salts  are  derived,  but  ir-bromonitrocamphor  seems  to  be  the 
only  nitro-compound  of  which  the  two  isodynamic  forms  have  been 
obtained  in  well-defined  crystals  of  ascertained  purity,  and  submitted 
to  crystallographic  measurement  (L.  and  El.,  loe.  oil.).     The  results 

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AND  ALLIED  C0MP0T7NDS.  229 

obtained  in  the  two  series  of  nitro-com pounds  differ  in  several 
important  respects,  and  the  experiments  described  in  the  following 
paragraphs  are,  therefore,  given  in  the  form  of  a  comparison. 

Action  qf  Adda  on  Aqueous  SoluUona  qf  the  Salts. — ^The  labile 
peeudo-forms  isolated  by  Hantzsch  and  Schultze  were  prepared  by 
the  action  of  mineral  acids  on  a  solution  of  the  sodium  salt,  whilst 
organic  acids,  such  as  carbonic  and  acetic,  on  account  of  their  slower 
action,  were  found  to  give  either  the  normal  form  or  a  mixture  of 
the  two.  As  this  method  appeared  to  afford  a  ready  means  of  pre- 
paring pseudonitrocamphor  and  normal  n^bromonitrocamphor,  attempts 
were  made  to  isolate  these.  On  acidifying  a  dilute  solution  of  potas- 
sium n^bromopseudonitrocamphor,  a  crystalline  powder  was  obtained 
which  showed  an  initial  specific  rotatory  power  [a]  =+116°  in  a 
3-33  per  cent,  solution  in  benzene;  the  product  was,  therefore,  a 
mixture  containing  only  30  per  cent,  of  the  pseudo-form.  Moreover, 
on  attempting  to  isolate  pseudonitrocamphor  by  the  action  of  mineral 
acids  on  a  solution  of  one  of  its  salts,'a  mixture  was  again  obtained  in 
every  experiment,  the  proportions  of  the  two  forms  being  approxi- 
mately the  same  as  that  in  which  they  exist  in  solution;  in  one 
experiment,  a  known  weight  of  nitrocamphor  was  dissolved  in  aqueous 
potash,  precipitated  with  hydrochloric  acid,  drained  on  a  filter-pump, 
and  immediately  dissolved  in  a  known  volume  of  alcohol ;  the  solution 
gave  a  constant  rotatory  power,  [a]^  »  -  9° ;  the  first  reading  of  the 
polariscope  was  obtained  within  15  minutes  from  the  time  when 
the  acid  was  added  to  the  salt  solution,  and  no  change  was  subse- 
quently observed.  If  the  pseudo-form  be  assumed  to  be  the  first 
product  of  the  action,  the  production  of  a  mixture  of  the  two  forms 
can  be  readily  explained  as  due  to  the  catalytic  influence  of  the  salts 
present  during  precipitation  (compare  p.  221),  but  it  is  also  possible 
that  both  forms  are  produced  directly  from  the  potassium  salt  by  the 
action  of  the  acid,  without  being  first  thrown  down  in  the  pseudo-form. 

Nature  qf  the  Isomeric  Chofnge^  Complete  or  Incomplete, — It  has  been 
stated  by  Hantzsch  and  Schultze  that  the  conversion  of  the  pseudo- 
into  the  normal  nitroparaffins  is  complete,  that  is,  that  the  isomeric 
change  is  non-reversible;  '*  whilst  thus  the  groups -CHj* CO-  and 
-CHIC(OH)-  are  both  stable  to  a  certain  extent  in  the  free  state,  of 
the  groups  -CHg-NOg-  and  -CHINOsH,  the  first  alone  is  stable" 
(ffttti.,  p.  2267).  This  statement  is  directly  opposed  to  the  equilibrium 
which  has  been  shown  to  exist  between  the  two  forms  of  nitrocamphor 
and  ir-bromonitrocamphor,  and  is  also  contradicted  by  the  statement 
of  Konowaloff  {loe.  ct^.),  that  the  labile  pseudo-form  of  xylylnitro- 
methane,  which  only  differs  from  phenylnitromethane  by  the  presence 
of  two  additional  methyl  groups  in  the  benzene  nucleus,  is  converted 
into  a  mixture  of  the  normal  and  pseudo-forms,  containing  also  a 

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230  LOWRY:  STUDIES  OF  THE  TEBPENES 

small  amount  of  the  corresponding  aldehyde.  It  appears,  therefore, 
to  be  more  probable  that,  even  in  the  case  of  phenylnitromethane  and 
parabromophenylnitromethane,  an  equilibriom  is  established  between 
the  two  forms  in  solution  and  in  the  liquid  state,  although  the 
quantity  of  the  pseudo-form  may  be  too  small  to  produce  any  marked 
coloration  with  ferric  chloride. 

Action  qf  Ferric  Chloride. — ^In  almost  every  case  of  dynamic  iso- 
merism that  has  been  studied  up  to  the  present,  the  formation  of  a 
coloured  ferric  salt  has  been  made  use  of  to  distinguish  the  hydroxylic 
modification,  and  it  has  even  been  made  the  basis  of  rough  quantitative 
measurements.  In  the  case  of  nitrocamphor  and  x-bromonitro- 
camphor,  this  test  is  not  available,  as  both  isodynamic  forms  give  the 
same  coloration  with  ferric  chloride ;  in  order  to  make  sure  of  thus 
result,  crystals  of  normal  and  pseudo-7r-bromonitrooamphor  were 
crushed  and  dissolved  in  equal  quantities  of  cold  spirit,  and  a  drop 
of  alcoholic  ferric  chloride  was  immediately  added  to  each ;  not  the 
slightest  difference  could  be  detected  between  the  two  solutions, 
either  in  the  depth  of  colour  or  in  the  velocity  with  which  it  was 
produced.  This  unusual  behaviour  is  most  readily  explained  as  being 
due  to  the  accelerating  effect  of  ferric  chloride  on  the  isomeric  change, 
an  effect  which  has  already  been  shown  to  be  produced  by  neutral 
salts ;  it  would,  therefore,  appear  that,  under  the  influence  of  the  ferric 
chloride,  equilibrium  is  reached  during  the  second  or  two  that  is 
required  for  the  development  of  the  coloration. 

Action  of  Nitrous  Acid  on  NUroeampkor. — It  has  been  stated  by 
Hantzsch  and  Schultze  that,  when  suspended  in  ether,  all  pseudo- 
nitro-compounds  and  their  derivatives  yield  a' sky-blue  coloration  if 
acted  on  with  hydrogen  chloride  or  acetic  chloride.  This  does  not 
occur  in  the  case  of  nitrocamphor,  but  a  similar  coloration  can  be 
produced  by  the  action  of  nitrous  acid.  If  a  drop  of  dilute  sulphuric 
acid  is  added  to  an  aqueous  solution  of  potassium  pseudonitrocamphor 
and  potassium  nitrite,  a  transient  blue  colour  is  produced,  which 
rapidly  passes  to  green  and  then  to  yellow  ;  the  ultimate  product  is  a 
yellow  oil,  which  decomposes  almost  explosively  when  heated,  giving 
off  a  considerable  quantity  of  gas  and  leaving  a  solid  cake  of  oamphor- 
quinone.  From  analogy  to  other  secondary  nitro-compounds,  it  is 
probable  that  the  blue  substance  is  the  peeudomtrcl^  and  that  this 
passes  by  loss  of  2N0  into  camphorquinone,  as  shown  by  the  formulas 

The  blue  coloration  observed  by  Hantzsch  and  Schultze  must  obvi- 
ously be  due  to  the  nitrous  acid  which  is  liberated  by  the  decomposition 
of  the  unstable  pseudonitroparaffins.^ 


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AND  ALLIED  COMPOUNDS.  231 

Mokevla/r  Weights. — It  has  been  shown  by  Hantzsch  and  Schnltze 
that  pseudophenylnitromethane  is  largely  bimolecnlar,  and  that  when 
it  is  dissolved  in  benzene  the  molecular  weight,  as  determined  from 
the  freezing  point  of  the  solution,  falls  slowly  from  210  to  141  during 
the  period  that  elapses  before  equilibrium  is  reached ;  the  molecular 
weight  of  the  normal  form,  calculated  from  the  formula  C^HYNOg,  is 
137.  A  similar  decrease  of  molecular  weight  has  been  shown  to  occur  in 
a  freshly  diluted  solution  of  formaldehyde  (Eacheweiler  and  Groesmann, 
Annalen,  1890,  258^  103).  On  making  an  experiment  with  pseudo- 
ff^bromonitrocamphor,  the  freezing  point  of  the  freshly  prepared  solu- 
tion was  found  to  be  0*492^  lower  than  that  of  the  benzene  used  as 
a  solvent;  when  the  solution  had  been  brought  to  a  condition  of 
equilibrium  by  keeping  it  at  atmospheric  temperature  during  6  days  and 
then  momentarily  warming  to  the  boiling  point,  the  depression  of  the 
freezing  point  was  0'652%  the  difEerence  between  the  two  values  being 
no  greater  than  that  which  might  be  produced  by  the  evaporation 
of  the  benzene.  The  conoentration  of  the  solution  was  found  to  be 
2'946  grams  per  100  grams  of  benzene,  and  the  calculated  molecular 
weight  of  the  substance  was  261 ;  from  this,  it  may  be  concluded 
that  both  the  isodynamic  forms  of  ir-bromonitrocamphor  are  mono- 
molecular,  the  theoretical  value  for  a  single  molecular  proportion 
being  M»  271. 

A  determination  of  the  molecular  weight  of  nitrocamphor  in  solu- 
tion in  benzene,  by  the  freezing  point  method,  gave  the  value  M  =>  208 
(calo.  107). 

The  CryetoMieation  qf  Dyiwmic  leomerides. 

CryftaUieation  frcm  SohUion. — ^The  behaviour  of  ir-bromonitro- 
camphor  affords  a  good  illustration  of  the  laws  which  govern  the 
crystallisation  of  isodynamic  substances,  and  as  these  do  not  appear 
to  have  been  previously  discussed,  a  short  account  of  them  is  given 
here.  For  each  form  there  will  be  a  true  eolubilUy  which  is  inde- 
pendent of  the  isomeric  change,  but  as  the  isomeride  is  also  present 
in  the  solution  when  equilibrium  is  reached,  the  quantity  of  the  sub- 
stance ultimately  dissolved,  or  the  apparefnA  aolvbUiiyy  will  always  be 
greater.  Thus,  every  gram  of  pseudo-n^bromonitrocamphor  is  in 
equilibrium  in  solution  with  17  grams  of  the  normal  form,  and  the 
apparent  solubility  will,  therefore,  be  18  times  as  great  as  the  true 
solubility,  whilst  for  the  normal  form  the  ratio  will  be  18/17.  In  the 
ease  of  w^bromonitrocamphor,  the  apparent  solubilities  of  the  two  forms 
are  very  nearly  the  same,  as  a  mixture  of  the  two  is  usually  obtained 
on  crystallisation ;  that  of  the  normal  form,  however,  is  slightly  the 
larger,  as  the  pseudo-form  is  always  the  first  to  separate  from  solution ; 
for  the  sake  of  definiteness,  it  may  be  assumed  that  the  true  solu- 


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232  LOWBY:  STUDIES  OF  THE  TERPENES 

bilities  of  the  normal  and  pseudo-forms  are  in  the  ratio  of,  say,  19  : 1, 
in  which  case  the  apparent  solubilities  would  be  in  the  ratio  of  19  :  17. 
On  allowing  a  solution  of  ii^bromonitrocamphor  in  chloroform  to  evapo- 
rate, the  pseudo-form  is  observed  to  separate  first,  and  as  the  isomeric 
change  always  proceeds  in  such  a  direction  as  to  maintain  the  equi- 
librium, the  whole  of  the  substance  can  be  obtained  in  this  form  if 
the  crystallisation  is  sufficiently  slow.  If^  however,  evaporation  takes 
place  more  rapidly,  the  quantity  of  the  pseudo-form  in  the  solution 
will  decrease,  and,  when  the  proportion  falls  to  lees  than  one-twentieth 
of  the  total  quantity  of  substance  in  solution,  the  normal  form  will 
begin  to  separate,  and  both  forms  will  then  crystallise  out  side  by 
side ;  for  this  reason,  it  has  been  observed  that  the  normal  form  only 
separates  in  the  last  stages  of  the  evaporation,  and  it  is  only  the  com- 
plete disappearance  of  the  solvent  that  saves  it  from  being  re-dissolved 
and  converted  into  the  less  soluble  pseudo-form. 

In  the  case  of  a  substance  like  nitrocamphor,  in  which  the  form  that 
predominates  in  solution  is  the  first  to  separate,  there  will  not  be  any 
marked  decrease  in  the  proportion  present  in  the  solution  unless  the 
crystallisation  is  extremely  rapid,  and  even  then  the  pseudo-form  can 
only  separate  in  a  very  small  proportion,  and  would  appear  merely  as 
an  impurity  in  the  normal  form.  For  this  reason,  it  is  very  easy  to 
obtain  normal  nitrocamphor  in  a  pure  state,  and  no  indication  is 
obtained  of  the  presence  of  the  pseudo-form  in  the  crystals  even  when 
the  substance  separates  from  solution  very  rapidly. 

Fusion. — When  ?r-bromonitrocamphor  is  carefully  fused  on  a  glass 
slide  and  allowed  to  cool,  crystallisation  sets  in,  and  when  examined 
under  a  microscope  between  crossed  Nicols,  the  slide  is  seen  to  be 
covered  with  a  brilliant,  microcrystalline  figure ;  the  appearance  of 
the  image  varies  considerably,  but  radiating  lines  of  minute  vacuum 
bubbles,  caused  by  the  contraction  of  the  substance  on  solidification, 
are  usually  present,  and  appear  to  be  somewhat  characteristic  of  the 
substance.  When  examined  with  an  objective  of  higher  power,  bi- 
axial interference  figures  are  seen,  which  show  a  +  double  refraction ; 
the  substance  that  crystallises  out  under  these  conditions  is,  there- 
fore, the  pseudo-form,  since  the  normal  form  gives  a  uniaxial  inter- 
ference figure  with,  double  refraction  (L.  and  K.,  loc.  cit.) ;  the 
separation  of  the  pseudo-form  from  a  mixture  which  probably  consists 
chiefly  of  the  normal  form,  is  a  somewhat  striking  illustration  of  the 
difference*  in  their^  mutual  solubility,  and  recalls  the  similar  result 
obtained  on  crystallising  from  solution.  Under  ordinary  conditions, 
a  mixture  of  the  two  forms  is  obtained  on  cooling  the  fused  sub- 
stance, just  as  a  mixture  is  obtained  on  rapid  crystallisation  from 
solution ;  a  specimen  that  had  been  fused  in  a  test-tube  and  rapidly 
cooled  showed  an  initial  specific  rotatory  power  [a]|>=  -i-3^  in  a  3*30^ 

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AND  ALLIED  COMPOUNDS.  233 

per  cent,  solution  in  benzene  at  17%  and  therefore  contained  23  per 
cent,  of  the  pseudo-,  and  77  per  cent,  of  the  normal  form ;  this  result 
does  not  indicate  the  composition  of  the  fused  substance^  but  since 
the  pseudo-form  is  the  first  to  crystallise,  it  may  be  regarded  as 
giving  a  maximum  limit  to  the  percentage  of  this  in  the  liquid 
product. 

After  fusion,  all  the  modifications  of  n^bromonitrocamphor  remelt  at 
126^  (L.  and  K.,  he.  eit.\  and  this  temperature,  therefore,  must  repre- 
sent the  point  at  which  the  solid  pseudo-form  can  exist  in  stable 
equilibrium  with  the  liquid  mixture.  At  this  temperature,  the 
solubility  of  the  pseudo-form  in  the  fused  normal  form  must  be 
exactly  equal  to  the  percentage  in  which  it  exists  in  equilibrium  with 
it  in  the  liquid  state ;  in  the  case  of  ir-bromonitrocamphor,  this  point, 
which  maybe  called  the  '*  equilibrium  temperatuo'e,^'  lies  16°  below  the  true 
melting  point  of  the  pseudo-form.  The  true  melting  point  of  normal 
v-bromonitrocamphor,  which  is  given  by  Lapworth  and  Kipping  as 
108°,  lies  below  the  equilibrium  temperature;  but  it  is  somewhat 
difficult  to  observe  this  melting  point,  as  the  fused  substance  rapidly 
undergoes  isomeric  change  and  is  converted  into  the  solid  pseudo-form, 
after  which  it  melts  again  at  126°. 

When  fused  nitrocamphor  is  allowed  to  cool,  it  does  not  crystallise, 
but  solidifies  in  an  amorphous  condition,  indicating  that  the  mutual 
solubility  of  the  two  forms  is  greater  than  in  the  preceding  case.    The 
initial  specific  rotatory  power  of  a  recently  fused  specimen  was  found 
to  be  [a]D=  -7°  in  a  5  per  cent,  solution  in  chloroform  at  17°, 
corresponding  with  the  presence  of  about  10  per  cent,  of  the  pseudo- 
form  ;  as  the  forces  of  crystallisation  do  not,  come  into  play,  it  may 
be  assumed  that  these  numbers  correspond  also  with  the  composition 
of  the  fused  substance.     The  condition  of  equilibrium  in  solution  is 
reachedy  on  the  average,  when  about  7  per  cent,  of  the  substance  is  in 
the  pseudo-form,  and  this  experiment  shows  that,  at  a  temperature 
some  80°  higher,  the  proportion  of  the  pseudo-form  present  in  the 
fused  product  is  not  materially  greater,  since  the  figure  given  above 
is  probably  too  high  on  account  of  the  formation  of  the  anhydride 
during  fusion.    The  presence  of  both  normal  and  pseudo-nitrocamphor 
in  the  liquid  substance,  and  their  great  mutual  solubility,  affords  a 
ready  explanation  of  the  large  amount  of  oil  that  is  obtained  in 
preparing  it,  for  a  relatively  small  amount  of  a  third  substance, 
present  as  an  impurity,  would  suffice  to  prevent  the  mixture  from 
crystallising. 

LimiUa  of  StdbilUy. — ^The  term ''  stability  limits,"  or  *'  cippareTU  melting 
pakU,"  has  been  introduced  by  Knorr  {Annahny  1896, 293,  70  and  88)  to 
indicate  the  temperature  at  which  the  solid  substance  undergoes 
isomeric  change,  the  product  being  usually  a  liquid  mixture  of  the  two 


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234  LOWRY:  STUDIES  OF  THE  TBRPENES 

forms.  In  the  case  of  normal  ?r-bromonitrocamphory  the  substance 
only  melts  when  heated  rapidlj  to  a  temperature  of  108^ ;  when  heated 
more  slowly,  it  is  converted  into  the  solid  pseudo-form,  and  then  melts 
at  126^;  for  this  substance,  the  stability  limit  is  probably  just  below 
the  true  melting  point.  In  the  case  of  normal  nitrocamphor,  the 
observed  melting  point  is  by  no  means  sharp  or  well-defined,  and  may 
be  regarded  as  merely  a  stability  limit.  For  pseudo-ir-bromo- 
nitrocamphor,  the  stability  limit  is  identical  with  the  '  equililnrium 
temperature '  at  which  the  substance  remelts  after  fusion,  but  this 
will  not  necessarily  be  so  in  other  cases ;  thus  there  would  be  a  definite 
stability  limit  or  apparent  melting  point  for  pseudo-  as  well  as  for 
normal  nitrocamphor,  but  there  is  no  equilibrium  temperature  for 
this  substance,  as  it  does  not  crystallise  again  after  fusion ;  thus  the 
equilibrium  temperature  always  represents  a  reversible  change,  whilst 
the  stability  limit  represents  a  non-reversible  change  in  the  case  of  one 
of  the  isodynamic  forms,  and  often  in  the  case  of  both.  The  in- 
stability of  the  solid  pseudo-forms  of  phenylnitromethane  and  para- 
bromophenylnitromethane  can  readily  be  explained  by  means  of  the 
stability  limits  and  the  equilibrium  temperature ;  as  isomeric  change 
takes  place  at  the  ordinary  temperature,  the  stability  limits  of  both 
pseudo-forms  must  obviously  lie  below  the  atmospheric  temperature, 
but  whilst  parabromophenylnitromethane  has  an  equilibrium  tempera- 
ture at  60°,  and  therefore  passes  without  melting  into  the  solid  normal 
form,  that  of  phenylnitromethane  is  below  the  atmospheric  tempera- 
ture, and  a  liquid  is  produced  as  the  change  takes  place. 

Vaport8atian» — So  far  as  I  have  been  able  to  ascertain,  the  isodynamic 
forms  described  in  this  paper  are  quite  stable  in  the  crystalline 
condition ;  it  must,  however,  be  remembered  that  a  very  small 
quantity  of  solvent  would  be  sufficient  to  convert  a  large  amount  of 
the  more  into  the  less  soluble  form,  and  the  complete  conversion  of 
(e.g.)  normal  into  pseudo-ir-bromonitrocamphor  might  even  be  effected 
by  the  vapour  of  a  solvent;  moreover,  the  conversion  of  the  labile 
into  the  stable  form  must,  in  any  case,  take  place  more  or  less 
rapidly  by  a  process  of  sublimation.  Just  as  in  the  case  of  solubility, 
there  will  be  a  true  and  an  appcMr&nt  vapour  pressure,  and  the  labile 
form  will  be  that  which  has  the  greater  apparent  vapour  pressure ;  in 
the  case  of  ?r-bromonitrocamphor,  this  is  evidently  the  normal  form 
which  has  the  greater  apparent  solubility  and  the  lower  melting 
point ;  the  following  experiment  appears  to  show  that  this  is  also  the 
case  with  nitrocamphor,  and  that  the  conversion  of  the  normal  into 
the  pseudo-form  actually  takes  place  by  a  very  slow  process  of 
sublimation. 

It  was  noticed  that  a  highly  purified  specimen  of  nitrocamphor,  when 
kept  in  a  stoppered  bottle  for  several  months,  acquired  a  sweetish 


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AND  ALLIED  COMPOUNDS.  235 

Bmelly  whilst  the  sides  of  the  bottle  became  clouded  over  with  a  thin, 
white  snblimate ;  the  amount  of  substance  thus  formed  was  exceed- 
ingly small,  but  when  the  bottle  was  rinsed  out  with  chloroform,  a 
dextrorotatory  solution  was  obtained,  which  showed  a  change  of 
rotatory  power  from  right  to  left ;  this  behaviour  is  what  might  be 
expected  f  roih  pseudonitrocamphor,  and  a  rough  estimate  of  the  initial 
specifie  rotatory  power  gave  the  value  [a]o  =  + 160°  ( ±  10°),  which  is 
slightly  less  than  the  values  previously  assumed  for  this  substance  and 
observed  in  the  case  of  its  anhydride;  that  the  sublimate  does  not 
consist  of  this  anhydride  is  shown  by  the  fact  that  it  does  not  become 
yellow  on  exposure  to  light,  and  also  by  the  changing  rotatory  power 
of  the  solution.  The  evidence  brought  forward  here  is  admittedly 
slender,  but  the  observation  seems  to  demand  some  such  explanation 
as  that  given  above. 

Dynamic  Isomerism. 

The  isomerism  of  normal  and  pseudo-^ir-bromonitrocamphor  and  of 
normal  and  pseudonitrocamphor  is  found  by  experiment  to  be  of  such 
a  nature  that  the  two  forms  can  only  exist  separately  in  a  stable  con- 
dition when  in  the  solid  state,  and  then  only  at  temperatures  below 
the  stability  limit ;  on  passing  into  the  fluid  state,  either  by  fusion  or 
by  dissolution  or  by  vaporisation,  a  reversible  isomeric  change  sets  in, 
and  after  a  longer  or  shorter  period  of  time  a  state  of  equilibrium  is 
reached  in  which  equal  numbers  of  molecules  of  the  normal  and 
pseudo-form  undergo  isomeric  change  in  any  given  interval  of  time. 
For  this  well-defined  type  of  isomerism,  it  appears  advisable  that  the 
term  **  dynamic  isomerism'*  should  be  used  as  being  more  significant 
than  the  other  terms  which  have  been  proposed,  and  in  order  to  recall  the 
dynamic  equUihritMn  which  exists  between  the  isomerides  in  the  fluid 
state ;  two  substances  which  behave  in  this  way  may  be  described  as 
being  '  isodynamic,'  or  they  may  be  referred  ^to  as  'isodynamic 
forms '  of  one  substance  (see  the  article  on  "  Isomerism "  by  Dr. 
Armstrong  in  Morley  andMuir's  edition  of  Waifs  Dictumary  qf 
Chemistry),  In  the  case  of  ^bromonitrocamphor,  equilibrium  is 
reached  in  solution  when  6  per  cent,  of  the  substance  is  in  the  pseudo- 
form,  and  the  isomeric  change  from  the  pseudo-  to  the  normal  form 
must,  therefore,  proceed  16  times  as  fast  as  the  change  in  the  reverse 
direction ;  from  the  velocity-constants  given  on  p.  228,  it  is  seen  that  in 
eaehhour  4'8  per  cent^  of  the  pseudo-form  and  0'30  per  cent,  of  the 
normal  form  underwent  isomeric  change  under  the  conditions  of  the 
experiment.  In  the  case  of  the  separate  molecules,  the  structure  will 
at  one  tame  be  that  of  the  normal  form,  and  at  another  that  of  the 
pseudo-form,  but  the  isomeric  change  will  only  take  place  somewhat 


Digitized  by  VjOOQIC 


236  lowry:  studies  of  the  terpenes 

slowly  ;  thu8|  in  the  experiment  referred  to,  the  average  duration  of 
the  two  phases  would  be  21  hours  and  13  days  respectively.- 

A  theory  similar  in  many  respects  to  that  of  dynamic  isomerism 
was  put  forward  in  the  year  1885  by  Laar  in  a  paper,  "  Ueber  die 
Moglichheit  mehrerer  Strukturformeln  fur  dieselbe  chemische 
Yerbindung"  {Ber.,  18,  648—657).  In  order  to  explain  the  fact 
that  many  chemical  compounds  are  capable  of  yielding  derivatives  of 
two  types,  and  that  conversely  many  interactions  which  might  be 
expected  to  yield  isomerides  actually  give  identical  products,  he 
assumed  that,  in  all  such  cases,  the  *  tautomeric '  substance  alternated 
backwards  and  forwards  between  the  configurations  represented 
by  the  two  alternative  structural  formulsB,  so  that  at  one 
moment  it  had  the  structure  represented  by  one  formula,  and  at 
another  moment  that  represented  by  the  other.  Thus  it  has  been 
found  that  the  same  substance  is  produced  by  the  action  of  nitrous 
acid  on  phenol  and  of  hydroxylamine  on  quinone,  and  Laar,  therefore, 
assumed  that  the  compound  was  continually  alternating  between 
OH  O 


the  phases  \       f       and      I       |    .     The  essential  difference  between 


^"0  i^OH 

Laar's  theory  of  tautomerism  and  that  of  dynamic  isomerism  con- 
sists in  the  fact  that  he  regards  the  phenomenon  as  intramolecular,  and 
not  intermolecular,  comparing  it  with  the  vibration  which  gives  rise  to 
the  spectra  of  incandescent  gases  and  contrasting  it  with  the  equi- 
librium of  dissociation.  Two  consequences  follow  from  this :  first,  he 
regards  all  isodynamic  bodies  as  homogeneous  substances  having  uniform 
properties,  whereas,  in  many  cases,  they  can  be  proved  to  be  mixtures 
of  two  isomerides  which  have  different  physical  properties;  second^ 
the  phases  of  the  substance  could  only  be  separated  by  cooling  to  the 
absolute  zero,  and  so  stopping  all  motion  in  the  molecule,  whereas 
actually  it  is  found  to  be  sufficient  in  most  cases  merely  to  bring  the 
substance  into  a  crystalline  form.  For  this  reason,  Laar's  speculative 
theory  has  been  generally  abandoned,  whilst  the  theory  of  '  dynamic 
isomerism  '  has  been  verified  in  a  large  number  of  examples. 

The  term  *  desmotropy*  was  introduced  by  Jacobson  (Ber.f 
1888,  21,  2628)  as  an  alternative  to  the  word  *  tautomerism,'  but  its 
meaning  was  narrowed  down  by  Hantzsch  and  Hermann  {Ber.^  1887, 
20,  2802),  who  suggested  that  the  term  should  be  used  only  for 
those  substances  of  which  two  solid  modifications  are  known.  Two 
consequences  have  followed  from  this :  first,  a  considerable  amount  of 
confusion  has  been  introduced  in  relation  to  the  difference  betweei) 


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iCHPh 


AND  ALLIBD  COMPOUNDS.  237 

polymorphism  and  dynamic  isomerism,  and  second,  according  to  the 
present  style  of  nomenclature,  ^^bromonitrocamphor  would  be 
described  as  ^  desmotropio/  whilst  nitrocamphor  would  be  merely 
*  tautomeric,'  although  the  isomerism  of  the  normal  and  pseudo- 
forms  is  of  precisely  the  same  nature  in  each  case. 

Two  years  previous  to  the  publication  of  Laar's  paper,  it  was 
shown  by  Baeyer  (^er.,  1883,  16,  2188)  that  certain  compounds  of 
the  indigo-group  were  capable  of  yielding  two  types  of  derivatives, 
although  they  were  not  themselves  known  in  more  than  one  of  the 
two  possible  isomeric  forms.  He,  therefore,  assumed  that  one  of  the 
isomerides  was  stable,  whilst  the  other  was  labile,  and  went  over 
immediately  into  the  stable  form  whenever  attempts  were  made  to 
prepare  it.  Thus,  pseudoisatin  is  not  known,  although  ethyl  pseudo- 
isatin  is  perfectly  stable,  and,  similarly,  pseudoindoxyl  is  known  only 
in  the  form  of  derivatives. 

C,H,-CO  <?,H,-CO  C,H,- 

N=rr:COH  NH CO  NEt- 

Isatin  (stable).  Fseadoisatin  (labile).  Stable  derivatiTe. 

C,H,-j:]OH              VeH^-gO               (f,^,-QO 
NH-i-CH  NH CHg  NH C=C 

Indozyl  (stable).  Pseadolndozyl  (labile).  Stable  deriyatiye. 

Baeyer's  hypothesis,  to  which  the  name  of  ^  paeudomeriam*  has  been 
given  by  Laar  {Ber,,  1886, 19,  730),  may  be  regarded  as  contemplating 
merely  a  limiting  case  of  '  dynamic  isomerism '  in  which  the  pro- 
portion of  one  of  the  isodynamic  forms  in  the  state  of  equilbrium  is 
infinitesimal,  so  that  the  isomeric  change  is  practically  complete,  and 
proceeds  only  in  one  direction. 

The  credit  of  recognising  the  possibility  of  dynamic  isomerism  and 
of  applying  it  to  explain  the  behaviour  of  substances,  such  as  hydro- 
cyanic acid,  which  yield  two  kinds  of  derivatives,  undoubtedly 
belongs  entirely  to  Butlerow.  In  a  paper,  ''Ueber  Isodibutylen  •" 
(Annalen,  1877,189, 44),  he  showed  that  the  products  of  oiddation  of  the 
substance  indicated  the  presence  in  it  of  two  isomeric  hydrocarbons, 

^>CH-  CH^-  CH:C<Jg3  and  ch'>^^'  ^^a'  OH^-  (K^J^, 
and  brought  forward  evidence  to  show  that,  in  presence  of  concen- 
trated sulphuric  acid,  there  is  a  state  of  equilibrium  between  the  two 
olefines,  the  intermediate  stage  being  probably  the  alcohol  or  alcohol 

sulphate,    ^^3>OH-CH2-CH-C(SO^H)<^g8.    He,  therefore,  sug- 

8 

gested  that,  in  other  cases,  a  similar  state  of  equilibrium  might  exist 
even  in  the  absence  of  a  catalytic  agent,  and  pointed  out  that  this 
would  fully  account  for  the  production  of  two  series  of  ethers  from 
YOU  hXXY.  H 

Digitized  by  VjOOQIC 


238  lowry:  studies  of  the  tebpenes 

hydrocyanic  and  other  allied  acids;  the  recent  statement  of  Knorr 
{Ber.y  1897,  30,  2389),  that  hydrocyanic  acid  and  other  '  tautomeric  ' 
liquids  are  composed  of  a  mixture  of  two  isomerides  in  equilibrium,  is, 
therefore,  identical  in  every  respect  with  the  idea  so  clearly  stated  by 
Butlerow  22  years  previously. 

To  Butlerow  belongs  also  the  credit  of  recognising  the  importance 
of  catalytic  agents  in  effecting  isodynamic  change.  These  substances 
at  least  increase  its  velocity,  if  they  do  not  underlie  the  isomeric  change, 
a  result  which  is  seen  very  clearly  in  the  action  of  bases  in  accelerating 
the  changes  of  rotatory  power  of  nitrocamphor  and  the  sugars ;  in 
many  instances,  therefore,  they  render  obvious  cases  of  isodynamic 
change  which  would  otherwise  proceed  too  slowly  to  be  observed.  To 
this  class  of  substances,  Butlerow's  isodibutylenes  obviously  belong, 
and  the  equilibrium  between  fructose,  glucose,  and  mannose,  when 
dissolved  in  dilute  potash,  affords  another  example  of  the  same  type, 
and  one  that  is  of  special  interest,  as  it  involves  the  equilibrium  of 
three  dynamic  isomerides.  Keference  may  also  be  made  here  to 
the  fact  that  whenever  two  optical  isomerides  become  isodynamic, 
either  alone  or  in  presence  of  catalytic  agents,  an  inactive  mixture 
will  always  be  formed.  To  the  former  class  of  substances  belong 
all  those  which  are  incapable  of  being  resolved  into  their  optical 
isomerides  by  reason  of  the  **  chaotic  "  nature  of  the  molecule,  whilst 
the  use  of  catalytic  agents  has  been  illustrated  by  Holleman  in 
the  action  of  dilute  potash  on  c^phenylglycollic  acid  {Bee.  Trav. 
Chim.j  1898,  17,  323)  and  of  acids  and  alkalis  on  the  tartaric  acids 
(t6u2.,  p.  66),  the  existence  of  an  equilibrium  being  indicated  in 
the  latter  case  between  the  dextro-,  Isbvo-,  and  meso-acids.  The 
marked  contrast  observed  between  the  behaviour  of  solutions  of 
nitrocamphor  when  dissolved  in  chloroform  alone,  and  when  in  presence 
of  a  trace  of  piperidine,  serves  to  suggest  the  question  as  to  whether 
a  catalytic  agent  is  not  essential  in  all  cases  of  isodynamic  change ; 
in  some  instances,  at  least,  this  appears  to  be  so,  but  in  the  fluid 
state  the  condition  of  a  single  dynamic  isomeride  must  be  regarded  as 
essentially  labile,  since  the  isomeric  change  might  be  brought  about 
by  the  action  of  a  minute  trace  of  alkali  from  the  glass  of  the  con- 
taining vessel,  and  it  is  possible  that  a  trace  of  the  second  isomeride 
might  prove  sufficient ;  in  any  case,  the  catalytic  agent  appears  to  be 
of  the  same  order  as  the  trace  of  moisture  that  is  probably  essential 
in  all  chemical  changes,  and  may,  perhaps,  be  regarded  as  supplying 
the  conditions  necessary  for  the  production  of  a  conducting  circuit  in 
the  liquid.  It  is,  however,  of  the  utmost  importance  to  notice  that, 
whilst  catalytic  agents  have  a  very  great  effect  on  the  velocity  of 
isomeric  change,  they  do  not  produce  any  marked  alteration  in  the 
eqtiilibrium  which  is  ultimately  established.     The  assumption  made  by 


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AND   ALLIED  COMPOUNDS.  239 

Schiff  (Ber.,  1898, 31,  602)  that  ethylic  acetoaoetate  could  be  converted 
completely  into  the  enolic  or  ketonic  form  by  the  addition  of  a  trace  of 
sodium  ethoxide  or  of  piperidine  is  obviously  impossible,  and  has  been 
completely  disproved  by  the  experimental  work  of  Schaum  (Ber., 
1898,  31,  1964),  who  has  shown  that  the  physical  properties  of  the 
substance  remain  unchanged  under  these  conditions;  similar  results 
have  been  obtained  in  the  case  of  nitrocamphor,  and  from  these  it  is 
obvious  that,  far  from  causing  the  complete  conversion  of  the  mixture 
into  one  of  the  dynamic  isomerides,  these  agents  are  exactly  those 
which  would  most  rapidly  bring  about  an  equilibrium  between  the  two 
forms. 

A  number  of  cases  are  known,  and  have  been  studied  in  detail,  in 
which  isomerides  that  are  stable  at  ordinary  temperatures  become 
isodynamic  when  the  temperature  is  raised ;  the  results  obtained  in 
these  cases  are  of  considerable  importance  in  helping  to  solve  the 
more  difficult  problems  presented  by  substances  which  are  isodynamic 
at  ordinary  temperatures.  Thus,  in  the  case  of  the  stereoisomeric 
dibromotolanes,  it  has  been  shown  by  Wislicenus  {DekaTuUsschrift, 
"  TJeber  die  XJmsetzung  stereoisomerer  ungesiittigter  organischer 
Yerbindungen  ineinander  bei  hoherer  Temperatur,"  Leipzig,  1890)  that 
at  210^  an  equilibrium  exists  in  which  the  cia-  and  ^ran^-forms  are 
present  in  the  proportion  of  48  :  52. 

(48  per  cent.)  ^»^^fl*^^  —    ^aHfi'C-Br      (52  per  cent.). 

A  similar  equilibrium,  although  complicated  by  secondary  actions, 
occurs  in  the  conversion  of  ammonium  thiocyanate  into  thiourea, 

NH^-ONS  :::^  CS(NK^)^ 
(Volhard,  J.  pr.  Chem,,  1892,  [ii],  0,  11).  The  case  which  has  been 
studied  most  fully  is,  however,  that  of  the  isomeric  hexachloro- 
cycloketopentenes,  described  by  Kiister  in  a  paper,  **  TJeber  den 
Yerlauf  einer  umkehrbaren  Beaktion  erster  Ordnung  in  homogenem 
System"  (Zeit.  physikal.  CJi^m,,  1895,  18,  161);  the  equilibrium 
between  these  substances,  which  is  reached  in  about  12  hours  at  210^, 
corresponds  with  a  mixture  of  61*4  per  cent,  of  the  )S-cyclopentene 
with  38*6  per  cent,  of  the  y-compound, 

QQ\ nrj]  G0\ CCl 

08=61-4  per  cent.)  J^j3^^j>C0   —   y^j_^^j^CO(y«38-6percent.). 

In  all  these  cases,  equilibrium  is  reached  only  slowly  at  210°,  and 
at  ordinary  temperatures  the  isomerides  appear  to  be  stable ;  they 
can,  therefore,  be  separated  by  fractional  crystallisation,  or  even  by 
means  of  chemical  agents;  thus  Kiister  was  able  to  estimate  the 
quantity  of  the  )8-compound  in  a  mixture  of  the  two  isomerides  by 

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240  LOWUY  :  STUDIES   OF  THE  XfeRPENES 

converting  it  into  the  sparingly  solable  anilide,  OgClgO-NHPh, 
the  y-compoiind  remaining  in  solution  unchanged. 

When  the  isomeric  change  proceeds  with  even  moderate  rapidity 
at  a  temperature  of,  say,  100%  it  will,  as  a  rule,  only  be  possible  to 
separate  the  two  isomerides  by  crystallisation,  as  chemical  agents  are 
found  to  have  a  great  accelerating  effect  on  the  change  ;  the  various 
modifications  of  ethylic  diacetylsuccinate,  studied  by  Knorr  (AnnaHen^ 
1896,  293,  70),  were  separated  by  fractional  crystallisation,  and 
may  be  regarded  as  typical  of  this  group ;  so,  too,  the  ketonic  and 
enolic  forms  of  ethylic  anilidobenzylacetoacetate,  described  by  Schiff 
{Ber.y  1898,  31,  205),  can  be  fused  several  times,  or  crystallised 
repeatedly  from  spirit  before  equilibrium  is  reached  between  the  two 
forms, 

CHg-OO-CH-OOOEt        _^    CH3-0(0H):C-000Et 

CHPh-NHPh    *^  CHPh-NHPh 

and  may,  therefore,  be  regarded  as  belonging  to  the  same  class  of 
dynamic  isomerides  as  the  diacetylsuccinic  ethers. 

Ti^Bromonitrocamphor  is  an  example  of  a  substance  in  which  the 
isomeric  change  proceeds  at  a  moderate  rate  even  at  ordinary  tem- 
peratures, so  that  the  two  forms  cannot  be  separated  by  the  usual 
methods  of  fractional  crystallisation.  In  this  case,  advantage  is  taken 
of  the  fact  that  the  dynamic  isomerides  have  nearly  the  same 
apparent  solubility,  so  that,  on  allowing  a  solution  in  chloroform  to 
evaporate  to  dryness,  the  two  forms  crystallise  out  side  by  side,  and 
can  be  picked  out  mechanically.  This  appears  to  form  almost  the 
limiting  case  in  which  the  dynamic  isomerides  can  be  separated,  and 
when  the  velocity  of  change  is  greater,  or  the  substances  are  liquids 
at  ordinary  temperatures,  the  task  must  be  regarded  as  practicable 
only  by  the  application  of  extraordinary  methods. 

In  some  cases,  it  is  possible  to  prepare  the  isodynamic  forms  of  a 
substance  by  chemical  methods,  such  as  those  employed  by  EUintzsch 
and  Schultze,  and  by  KonowaJoff  in  the  case  of  the  nitroparaffins  (see 
p.  228),  namely,  conversion  into  the  sodium  salt  and  acidification  with 
mineral  acids.  This  was  done  by  W.  Wislicenus  in  the  case  of  ethylic 
phenylformylacetate  {Awruden,  1896,  291,  147),  and  the  method  has 
recently  been  applied  successfully  by  Babe  {Bw,j  1899,  32,  84)  in  the 
case  of  ethylic  ethylidene-  and  benzylidene-acetoacetates, 

CHj-OO-CjUH-COOEt  CHg-CO-CjJH-COOEt 

CHg-CH  and  CeH^-CH  ; 

CHg-CO-CH-COOEt  CHj-CO-CH-COOEt 

in  the  case  of  nitrocamphor,  it  was  not  found  possible  to  prepare  the 
pseudo-form  in  this  way.     In  connection  with  the  influence  whicl^ 


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AND  ALLIED  COMPOUNDS.  241 

bases  and  salts  have  been  shown  to  have  on  the  mutarotation  of 
nitrocamphor,  it  is  of  interest  to  notice  that,  in  order  to  separate  the 
enolic  forms  described  by  Babe,  it  was  necessary  to  use  an  excess  of 
the  mineral  acid  so  as  to  neutralise,  as  far  as  possible,  the  accelerating 
effect  of  the  bases  in  the  solution  ;  this  result  is  directly  in  accord- 
ance with  the  views  put  forward  on  p.  221  as  to  the  action  of  these 
catalytic  agents. 

The  recent  work  of  Schiff  on  ethylic  acetoacetate  is  of  interest  as 
showing  how  dynamic  isomerides  may  sometimes  be  prepared  with  the 
help  of  catalytic  agents.  In  the  condensation  of  benzalaniline  with 
ethylic  acetoacetate,  he  was  able  to  show  (Ber.,  1898,  31,  601)  that  in 
presence  of  a  trace  of  sodium  ethozide  only  the  enolic  form  of  the 
additive  compound  was  produced,  whilst  a  trace  of  piperidine  led  to  the 
production  of  the  ketonic  form.  This  action  was  assumed  by  Schiff 
to  be  due  to  the  complete  conversion  of  the  ethylic  acetoacetate  by 
these  catalytic  agents  into  the  enolic  or  ketonic  form ;  the  incorrect- 
ness of  this  view  has  already  been  referred  to,  bub  the  influence  of  the 
two  kinds  of  bases  can  be  readily  explained  by  means  of  equations 
similar  to  those  which  have  already  been  used  in  the  case  of  nitro- 
camphor,  thus : 

COH  _  CONa  CisHijN 

or     '6b.      +NaOEt...M     ^^^qj.       _ 


MsN' 


COOEt  COOEt 

CONa  _  COH 

C.C„H,3N  +  S0E*  *  •  C.O„H, -  +  NaOEt. 

COOEt  COOEt 


9I-S 


COH 


«H     +C5HUN  r:  pNo,H„  c»»^»N 
9H. 

Et  COOEt 

The  assumptions  that  are  here  made  are  (1)  that  the  bases  combine 
more  readily  with  the  ether  than  with  its  benzalaniline  compound,  and 
are,  therefore,  more  effective  in  bringing  about  isomeric  change  in  the 
former  substance ;  the  reversed  action  in  the  above  equations  would 
then  be  only  slight,  as  is  indicated  by  the  dotted  arrows ;  (2)  that  the 


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242  LOWRY  :  STUDIES  OF  THE  TERPENES 

benzalaniline  interacts  more  readily  with  these  basic  compounds  than 
with  the  free  ether. 

On  account  of  the  equilibrium  which  exists  in  a  mixture  of  dynamic 
isomerides,  the  addition  to  it  of  a  chemical  agent  which  interacts  with 
only  one  form  will  necessarily  bring  about  the  complete  conversion 
of  the  substance  into  that  form.  In  this  way,  normal  nitrocamphor  is 
immediately  converted  by  alkalis  into  a  salt  of  the  pseudo-form, 
whilst  the  anhydride  of  the  latter  is  produced  on  heating  it ;  on  the 
other  hand,  the  salts  are  reconverted  into  normal  nitrocamphor  by 
acidifying  a  solution  and  crystallising  the  product,  whilst  the  action 
of  bromine  and  chlorine  yields  the  normal  bromonitro-  and  chloronitro- 
camphors  described  in  Fart  I.  of  this  paper  (Trans.,  1898,  73,  986). 
For  this  reason,  chemical  methods  cannot  be  used  in  studying  sub- 
stances which  are  isodynamic  at  ordinary  temperatures,  and  physical 
methods  must  be  relied  on  almost  entirely.  This  objection  applies 
also  to  the  use  of  agents,  such  as  benzalaniline,  which  yield  additive 
compounds  of  both  types,  and  it  is  somewhat  surprising  that  Schiff,  after 
having  demonstrated  the  enormous  influence  of  a  mere  trace  of  sodium 
ethoxide  on  the  interaction,  should  have  been  led  to  regard  the  forma- 
tion of  the  enolic  derivative  as  proving  that  the  ether  was  itself 
entirely  enolic.  It  appears  highly  improbable  that  the  enolic  form 
of  the  ether  should  persist  in  a  labile  state,  without  undergoing 
isomeric  change  under  the  influence  of  the  alkaline  salts  present 
during  its  preparation,  or  in  the  subsequent  distillation,  and  such  an 
assumption  would  only  be  justified  after  the  nature  of  the  ether  had 
been  definitely  established  by  physical  methods. 

The  only  chemical  method  that  appears  to  be  available  for  the  study 
of  dynamic  isomerism  consists  in  the  use  of  ferric  chloride  as  a  colour- 
test  for  the  presence  of  a  hydroxylic  modification ;  in  this  case,  how- 
ever, no  product  separates  out  from  the  solution,  and  as  only  a  minute 
quantity  of  the  substance  is  converted  into  ferric  salt,  the  equilibrium 
between  the  isodynamic  forms  is  not  disturbed  to  any  appreciable 
extent.  The  formation  of  the  coloured  ferric  salt,  and,  therefore,  the 
depth  of  the  coloration,  depend  on  the  'ratio  of  distribution'  of 
the  ferric  oxide  between  the  hydrochloric  acid  and  the  hydroxylic 
modification  of  the  isodynamic  substance,  and  as  the  latter  is  usually 
a  very  feeble  acid,  the  amount  of  ferric  salt  formed  will  be  exceedingly 
small  compared  with  the  quantity  of  ferric  chloride  added,  unless  the 
hydroxylic  modification  is  present  in  large  excess.  The  coloration  will, 
therefore,  give  a  rough  indication  of  the  extent  to  which  the  substance 
is  present  in  the  hydroxylic  form,  and  in  this  way  a  reversible  action 
may  be  made  use  of  to  study  cases  of  reversible  isomeric  change  in 
which  unreversible  actions  cannot  be  employed.  In  the  case  of  nitro- 
camphor and  of  ^-bromonitrocamphor,  the  test  breaks  down  on  account 

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AND  ALLIED   COMPOUNDS.  243 

of  the  catalytic  action  of  the  ferric  chloride,  and  this  may  be  regai*ded 
as  indicating  a  limit  to  the  usefulness  of  the  method. 

After  a  substance  has  been  found  to  exhibit  the  dual  chemical 
behaviour  characteristic  of  isodynamic  compounds,  physical  methods 
must  be  introduced  to  ascertain  whether  the  case  is  really  one  of 
dynamic  isomerism.  The  separation  of  two  solid  modifications  of  the 
substance  is  obviously  of  importance,  since  these  may  prove  to  be  the 
two  dynamic  isomerides,  but  this  must  not  be  assumed  to  be  the  case 
without  further  evidence,  as  the  differences  of  physical  properties  may 
be  due  simply  to  polymorphism.  In  order  to  establish  completely  the 
existence  of  dynamic  isomerism,  it  is  necessary  to  prove  further  that 
the  isomerism  persists  in  the  liquid  state^  although  it  is  not  essential 
for  this  purpose  that  the  isomerides  should  themselves  be  isolated ; 
when,  however,  this  can  be  done,  the  nature  of  the  isomerism  can  be 
best  established  by  examination  of  the  recently-fused .  substance,  or  of 
a  freshly-prepared  solution,  which  may  show  a  gradual  change  of  con- 
ductivity (Hantzsch  and  Schultze)  freezing  point  (ibid.),  refraction 
(Knorr),  or  rotatory  power.  In  other  cases,  a  substance  may  be  proved 
to  be  a  mixture  of  dynamic  isomerides  by  means  of  variations  in  its 
physical  properties  depending  on  the  treatment  it  has  previously  re- 
ceived ;  thus  the  changes  of  density  which  occur  in  ethylic  acetoacetate 
after  it  has  been  distilled  (Schaum),  may  be  regarded  as  affording 
proof  that  it  is  a  mixture  of  isomerides  or  of  polymerides,  since  the 
physical  properties  of  a  pure  substance  cannot  be  dependent  on  its 
past  history,  except  in  the  case  of  solids.  For  many  of  the  diketones, 
a  proof  of  the  presence  of  two  or  more  isonftrides  has  been  afforded 
by  the  determination  of  the  magnetic  rotation  by  Dr.  Perkin  (Trans., 
1892,  61,  801). 

Fdymorphiam,  depending  as  it  does  on  the  different  arrangement 
of  similar  molecules  in  the  crystal  structure,  represents  a  form  of 
isomerism  which  can  only  exist  in  the  solid  state  and  disappears 
immediately  on  dissolution  or  fusion ;  but  when,  on  the  other  hand,  the 
differences  in  crystalline  form  are  caused  by  differences  in  the 
structure  of  the  molecule,  the  distinction  between  the  various  forms 
will  persist  for  a  longer  or  shorter  time  in  the  liquid  state.  The 
behaviour  of  the  recently  fused  substance  or  of  a  freshly  prepared 
solution  affords,  therefore,  the  best  criterion  in  distinguishing  poly- 
merism  and  dynamic  isomerism  on  the  one  hand  from  polymorphism 
on  the  other ;  the  difficulty  of  observation  would,  of  course,  increase 
with  the  velocity  of  isomeric  change,  but  even  when  this  is  too  rapid 
to  be  detected,  the  constants  of  the  liquid  in  the  state  of  equilibrium 
would  be  those  of  a  mixture  of  the  two  forms,  and  the  composition 
of  the  substauoe  might  be  established  in  a  similar  manner  to  that 


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244       STtTDIES  OF  THE  TERPENES  AND  ALLIED  COMPOUNDS. 

by  whioh  the  constitution  of  the  liquid  diketones  has  been  ascer- 
tained by  Dr.  Perkin  from  their  magnetic  rotations. 

The  chief  points  of  difference  between  the  behaviour  of  isodynamic 
and  of  polymorphous  substances  are  due  to  the  time-factor  which  is 
always  involved  in  connection  with  dynamic  isomerides.  In  the 
crystallisation  of  polymorphous  substances  from  solution,  there  is  a 
sharp  temperature  limit  above  which  one  form  only  can  separate  in 
a  stable  condition,  whilst  below  it  another  form  is  stable ;  this 
limiting  temperature  represents  the  point  at  which  the  solubility 
curves  of  the  two  forms  intersect,  and  it  is  not  possible  for  them  to 
crystallise  out  together  from  solution  at  any  other  temperature.  If 
the  temperature  limit  lies  above  the  melting  point  of  the  substance 
or  the  boiling  point  of  the  solvent,  one  form  will  be  known  in  a 
labile  state  only,  and  the  addition  to  the  solution  of  a  crystal  of  the 
stable  form  will  be  sufficient  to  convert  it  completely  into  the  latter. 
The  behaviour  of  dynamic  isomerides  differs  only  from  that  just 
described  in  that  the  conversion  of  one  form  into  the  other  by 
isomeric  change  requires  a  longer  or  shorter  interval  of  time ;  the 
limiting  temperature  will  be  that  at  which  the  '  apparent  solubilities ' 
of  the  two  forms  are  equal,  but  on  account  of  the  time  required  for 
the  isomeric  change  to  take  place,  it  will  be  possible  for  the  two 
forms  to  crystallise  out  together  at  temperatures  considerably  removed 
from  this  point,  if  the  crystallisation  is  sufficiently  rapid ;  this 
behaviour  has  already  been  referred  to  in  connection  with  the 
crystallisation  of  ir-bromonitrocamphor  from  chloroform  solution,  and 
is  in  itself  sufficient  to  indicate  that  the  two  kinds  of  crystals  differ 
in  the  structure,  as  well  as  in  the  arrangement,  of  the  molecules. 

In  dealing  with  the  solid  substances,  similar  results  are  obtained, 
the  temperature  of  change  being  represented  by  the  intersection  of 
the  vapour  pressure  curves  of  the  two  forms.  But  whereas  the 
change  of  one  form  into  another  takes  place  at  a  sharp  temperature 
limit  in  cases  of  polymorphism,  there  will  be  no  such  sharp  temperature 
of  transformation  in  cases  of  dynamic  isomerism,  unless  the  isomeric 
change  takes  place  extremely  rapidly.  For  this  reason,  the  rapid 
change  of  crystalline  form  which  is  often  observed  when  a  substance 
is  fused  on  a  microscope  slide  and  allowed  to  cool  slowly  may  be 
regarded  as  specially  characteristic  of  polymorphism. 

In  conclusion,  I  desire  to  express  my  thanks  to  Dr.  Armstrong  for 
the  interest  he  has  taken  in  the  work  described  in  this  paper,  and 
for  the  help  he  has  afforded  in  carrying  it  out. 

Gh£mioal  Depabtment, 

City  and  Guilds  of  Londox  Institute, 

Central  Technical  Collbos,  South  Kensington. 


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ACTION  OF  AMMONIA  ON  ETHEREAL  SALTS  OF  OBGANIO  ACIDS.   245 


XXVIL — The  Action  of  Ammonia  on  Ethereal  Salts  of 
Organic  Acids. 

By  Siegfried  Euhemann. 

Thb  ethylic  salts  of  glutaconic  acid  and  its  homologaes,  as  shown  some 
time  ago  (Trans.,  1893, 63,  259,  874 ;  and  1898, 73,  350),  when  treated 
with  ammonia,  yield  respectively  aa'-dihydroxypyridine  and  the 
homologues  of  it  which  contain  an  alkyl  radicle  in  the  )8-position. 
Attempts  to  prepare  the  corresponding  ^^substitution  products  of 
this  dihydroxypyridine  have  already  been  made,  but  they  were  with- 
out result,  as  the  ethereal  salts  which  were  required  for  the  purpose 
could  not  be  obtained  by  the  interaction  of  the  alkyl  derivatives  of 
chloroform  and  ethylic  sodiomalonate  (Buhemann,  Ber,,  1896,  29, 
1016).  Those  pyridine  compounds,  as  well  as  the  derivatives  of  the 
dihydroxypyridine  with  alkyl  groups  in  the  y-  and  )9-positions  are,  how- 
ever, formed  from  the  ethylic  salts  which  are  produced  by  the  union  of 
ethylic  malonate  and  its  homologues  with  the  ethereal  salts  of  the 
acids  of  the  acetylene  series  (see  Michael,  J.  pr,  Chem,,  1887,  [ii], 
35,  349;  and  Ruhemann  and  Cunnington,  Trans.,  1898,73,  1006). 

The  ethylic  salts  of  the  acids  containing  an  acetylene  linking  (I 
have  as  yet  only  used  ethylic  phenylpropiolate)  combine  with  ethereal 
salts  of  fi-ketonic  acids,  such  as  ethylic  acetoacetate  and  ethylic 
benzoylacetate,  when  the  mixture  is  digested  with  sodium  ethoxide. 
This  reaction  does  not  yield  ethylic  salts  of  unsaturated  ketonic  acids, 
but  derivatives  of  a-pyrone,  the  union  being  accompanied  by  the  loss 
of  1  mol.  of  alcohol.  In  using  ethylic  acetoacetate  and  ethylic 
phenylpropiolate,  the  reaction  may  be  expressed  by  the  following 
equation. 
C-H^-  C : C-  COOaH,  +  CH^^^^^^s  _         CeH^-  C:CH-  COOC2H5 

^    ^  ^    ^  ^^CO-CHj  ■*  COOOgHfi-CH-OO-CHs 

"     COOO,H5-6:0(CH3)-^  +  ^2^«^- 

The  hope  of  transforming  these  compounds  into  derivatives  of  hydroxy- 
pyridine  has,  as  yet,  not  been  realised. 

This  paper  contains,  besides  the  record  of  the  work  done  in  this 
direction  up  to  the  present,  an  account  of  some  experiments  which 
have  been  undertaken  with  the  view  of  ascertaining  whether  the 
formation  of  imido-compounds  takes  place  when  ethereal  salts  of  other 
saturated  polycarboxyUc  acids  are  acted  on  by  ammonia,  as  in  the 
case  of  propanetetracarboxylic  acid  (Ruhemann  and  Cunnington,  loc* 


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246  RUHEMANN  :  THE  ACTION  OF  AMMONIA   ON 

cit.).     The  constitution  of  the  diamidoimide  of  this  acid  is,  no  doubt, 


one 


.00— CH-  OHj-  CONH2 
represented  by  the  formula  NH<^q Ao-'CONH  »    ^^^ 

may  expect  that  the  ethylic  salts  of  those  acids  which,  like  the  former, 
contain  carboxyl  groups  united  with  two  neighbouring  carbon 
atoms,  will  yield  analogous  substances,  as  with  them  the  conditions 
are  favourable  for  the  production  of  a  five-ring  compound.  The 
course  of  this  reaction  depends,  however,  not  only  on  the  position 
of  the  carbethoxyl  groups  in  the  molecule  of  the  ethylic  salt,  but  also 
on  the  nature  of  the  other  radicles  present.  Thus,  ethylic  )8-methyl- 
propanetetracarboxylate,  when  treated  with  ammonia,  does  not  give 
an  imidoamido-compound,  but  yields  the  tetramide  of  the  acid. 
Further  experiments  with  the  view  of  investigating  more  closely  this 
influence  are  in  progress. 


Experimental. 

Action  of  Ammonia   on    Ethereal  Salts   of  Saturated   Polyearboxylie 

Acids. 

EHiylic  P-methylpropo/TietetracarboxyleUe, 

C0NH,.C(CH3X:gg;!^4=^H 

which  is  formed  ^by  the  union  of  ethylic  citraconate  and  ethylic 
malonate,  is  very  slowly  acted  on  by  aqueous  ammonia,  and  only  a 
small  quantity  of  the  oil  disappears  after  6  to  8  weeks.  The  reaction, 
however,  is  accelerated,  although  it  remains  incomplete,  by  heating  the 
ethylic  salt  with  absolute  alcoholic  ammonia  at  150^  for  2  days ;  the 
amide,  being  sparingly  soluble  in  absolute  alcohol,  separates  out.  It 
crystallises  from  boiling  water  in  colourless  prisms,  which  begin  to 
decompose  at  about  255°  and  melt  at  270°  with  evolution  of  gas.  The 
following  numbers  were  obtained  on  analysis. 

0*2162  gave  44*5  c.c.  of  nitrogen  at  14°  and  762  mm.      N  =  24-28. 
CgHj^N^O^  requires  N  =  24*34  per  cent. 

In  order  to  ascertain  whether  the  above  difference  in  the  action  of 
ammonia  on  ethyUc  propanetetracarboxylate  and  its  homologue  is  due 
to  the  use  of  the  reagent  in  alcoholic  solution  and  to  the  temperature, 
the  experiment  was  repeated  with  ethylic  propanetetracarboxylate 
under  the  same  conditions.  The  solid  which  separated  after  heating 
the  ethylic  salt  of  propanetetraoarboxylic  acid  with  an  ezcesB 
of  alcoholic  ammonia  for  two  days  was  found  to  be  the  diamido- 
imide   of    the    acid.     Its  identity  with  the  product  obtained  with 


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ETHEREAL  SALTS  OF  ORGANIC  ACIDS.  247 

aqueous  ammonia  was  ascertained  by  a  comparison  of  the  physical 
properties  and  by  a  nitrogen  determination. 

0-2032  gave  38-6  c.c.  of  nitrogen  at  17°  and  732  mm.     N  =  2M5. 
CyHgNgO^  requires  N  =  2111  per  cent. 

Ethyl%cprop(mepentac€vrbox7/Iate,  nH<^^'"9^'^^^  ,  which 

CO — Cn*OH(CONH2)2 
reacts  with  ammonia  in  the  same  way  as  ethylic  propanetetracarb- 
ozylate  does,  yields  the  triamidoimide  of  the  acid,  the  oil  being 
completely  dissolved  when  left  in  contact  with  concentrated  aqueous 
ammonia  at  the  ordinary  temperature  for  8 — 10  days.  On  concen- 
trating the  ammoniacal  liquor,  crystals  separate  which  readily  dissolve 
in  boiling  water,  and,  on  cooling,  crystallise  in  colourless  needles 
which  melt  and  decompose  at  212°. 
On  analysis,  it  was  found  that 

0-1975  gave  40  c.c.  of  nitrogen  at  20°  and  759  mm.     N  =  2313. 
CgH^jN^Og  requires  N"  =  2314  per  cent. 

Ethylic  phenylpropcmetriearhooeylate,  ^6^6*^H'*^H(CONH-?  '  ^^^^ 
treated  with  aqueous  ammonia,  yields,  as  was  to  be  expected,  the  cor- 
responding triamide  ;  after  4 — 5  weeks,  the  oil  disappears,  and  a  solid 
separates  which  is  very  sparingly  soluble  in  alcohol  but  readily  in 
water,  and  crystallises  from  the  latter  in  colourless  needles  which 
begin  to  decompose  at  about  200°  and  melt  at  230°  with  evolution  of 
gas.  The  ammoniacal  mother  liquor,  on  evaporation,  yields  a  further 
crop  of  crystals  of  the  same  substance.     On  analysis, 

0-2035  gave  04320  CO2  and  0-1162  HjjO.     0  =  5789  ;  H  =  6-34. 

0-2068     „     30  c.a  of  nitrogen  at  19°  and  760  mm.     N=  1670. 

CijjH^gNgO,  requires  C  =  57*83 ;  H  =  602 ;  N  =  1686  per  cent. 


Action  of  Ammonia  on  Ethereal  Salts  qf  UnaatiJi/rated  Folycarboxylic 
Adda,     y-PhenyU  aui-dihydroxypyridine. 

The  starting  point  for  the  formation  of  this  dihydroxypyridine  isethylic 
phenylpropenetricarboxylate,  the  product  of  the  union  of  the  ethylic 
salts  of  phenylpropiolic  and  malonic  acids.    The  formula 

^6^6  ^^H(COOC2H5)2 
indicates  that  this  compound  may  be  regarded  as  ethyUc  phenyl- 
carboxyglutaconate,  and  that,  under  the  influence  of  ammonia,  it  would 
condense  to  a  pyridine  derivative.   This  reaction  takes  place,  yielding 
ethylic  y-phenyl-aba'dihydroxypyriddne-p'Carboocylate.    The  action  of  con- 

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248  RUHEMANN  :   THE   ACTION   OF   AMMONIA   ON 

centrated  aqueous  ammonia  on  ethylio  phenylpropenetricarboxylate  is 
very  slow,  only  a  small  quantity  of  the  oil  being  dissolved  in  the 
course  of  2 — 3  weeks,  but  the  action  is  more  rapid  with  alcoholic 
ammonia  at  100^ ;  after  several  days,  a  solid  separates,  which  is  the 
ammonium  derivative  of  the  pyridine  compound.  This  dissolves  in 
water  with  the  greatest  ease,  and  the  addition  of  hydrochloric  acid 
precipitates  a  crystalline  substance,  which  is  only  sparingly  soluble 
in  water  but  readily  in  ether  or  alcohol,  and  crystallises  from  dilute 
spirit  in  colourless  prisms  melting  at  200°.  Their  alcoholic  solution 
gives  a  purple  coloration  with  ferric  chloride.    The  result  of  the 

analysis  agrees  with  the  formula  ^    **  1*    ^       ^  Tl 

^        ^  CeHg-C^iCH— C-OH 

0-2136  gave  05070  00^  and  0-0980  H2O.    0  =  64-74 ;  H  =  5-09. 
0-2044     „     10  c.c.  of  nitrogen  at  20°  and  754  mm.     N  =  5-55. 
C^^HigNO^  requires  0  =  64-86  ;  H  =  501 ;  N  =  5-40  per  cent. 

Ethylic  phenylpropenetricarboxylate,  on  hydrolysis  with  baryta 
water,  yields,  as  Michael  (J,  pr,  Chem,,  1894,  [ii],  49,  20)  found, 
phenyglutaconic  acid,  and  this,  when  saturated  in  alcoholic  solution 
with  hydrogen  chloride,  is  transformed  into  ethylic'^ phenylgltUacanate  ; 
after  24  hours  standing,  water  is  added  to  the  solution,  the  oil  which 
separates  is  extracted  with  ether,  and  the  ethereal  layer  shaken  with 
sodium  carbonate.  The  substance  which  remains  on  evaporating  the 
ether  boils  at  186 — 187°  under  a  pressure  of  11  mm.  It  is  a  colourless 
liquid,  having  a  density  d  18718°«  11017.     The  result  of  the  analysis 

agrees  with  the  formula  C^Hj- CI  OH -0000^^5^ 

CH^-OOOCaHg 

0-2122  gave  0-5310  OOg  and  0-1348  H^O.     0  =  68-24^  H=7-05. 
OigHjgO^^requires  0  =  6870 ;  H  =  6-87  per  cent. 

The  transformation  of  ethylic  phenylglutaconate  into  the  phenyl- 

^N  ,  is  best  effected  by  heating 
H=0/0H 
it  with  concentrated  aqueous  ammonia  in  a  closed  tube  at  100°.  After 
2  days  digestion,  the  oil  completely  disappears ;  from  the  yellow  solution 
thus  obtained,  hydrochloric  acid  precipitates  a  crystalline  product  which 
dissolves  readily  in  hot  glacial  acetic  acid,  but  with  difficulty  in  boiling 
alcohol.  From  these  solvents,  it  separates  in  colourless  prisms  which 
melt  with  decomposition  at  254 — 255°.  The  yield  of  the  dihydroxy- 
pyridine  is  very  satisfactory,  5  grams  of  the  recrystallised  substance 
being  obtained  from  9  grams  of  the  ethylic  salt,  corresponding  with 
78  per  cent,  of  the  theoretical  yield. 


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ETHEREAL   SALTS   OF   ORGANIC   ACIDS.  249 

The  phenyldihydrozypyiidine  was  analysed,  with  the  following 
result. 

0-1955  gave  05060  COg  and  0-0855  H^O.    0  =  7058 ;  H  =  4-85. 
0-2646     „     17-6  CO.  of  nitrogen  at  18^  and  755  mm,     N  =  7-54. 
OjiHgNOg  requires  0  =  70-59  ;  H  =  4-81 ;  N  =  7'48  per  cent. 

The  chemical  behaviour  of  y^phenyldihydroxypyridine  is  analogous 
to  that  of  the  ^^-substituted  aa'-dihydroxypyridines.  In  alcoholic 
solution,  it  gives  a  red  coloration  with  ferric  chloride ;  dissolved  in 
ammonia,  it  forms,  on  adding  silver  nitrate,  a  yellow  silver  compound 
which  darkens  on  warming ;  the  ammoniacal  solution  turns  green  on 
exposure  to  the  air,  but  the  oxidation  takes  place  more  slowly  than 
with  the  dihydroxypyridines  which  contain  an  alkyl  group  in  the 
j9-position.  It  had  been  pointed  out  before  (Ruhemann,  Ber.^  1893, 
26,  1559)  that  the  j3-substituted  aa'-dihydroxypyridines  have  various 
properties  in  common  with  resorcinol,  one  of  them  being  the  forma- 
tion of  fluoresceins.  y-Phenyldihydroxypyridine  gives  this  reaction 
on  fusion  with  phtbalic  anhydride;  on  adding  dilute  potash  to  the 
product  formed,  a  solution  is  obtained  which  is  green  in  thin  and 
red  in  thick  layers ;  the  colour  is  discharged  by  acids. 

y-Phenyl'P-henzyl^'dihydroxypyridine, 

The  homologues  of  ethylic  malonate,  as  stated  above,  unite  with 
ethylio  phenylpropiolate  with  formation  of  ethylic  salts  of  unsaturated 
acids,  which  may  be  transformed   into   aa'-dihydroxypyridines   with 
alkyl  radicles  in  the  y-  and  /^-positions. 
„,,.«,,.        T  .      .       ,  0-H.-C:OH-OOOOA 

— The  reaction  has  been  carried  out  with  ethylic  benzylmalonate,  and 
the  union  of  this  salt  with  ethylic  phenylpropiolate  effected  as  in  the 
former  case.  The  mixture  of  the  two  compounds  does  not  become  warm 
on  adding  the  sodium  ethoxide,  but  if  the  mixture  be  heated  at  100° 
for  12  hours,  about  one-third  of  the  ethylic  salts  will  enter  into  com- 
bination, and  on  again  digesting  the  lower  boiling  portions  of  the  oily 
product  with  sodium  ethoxide,  a  satisfactory  yield  of  the  additive 
compound  is  obtained  ;  this  is  isolated  in  the  usual  manner.  It  boils 
at  260 — 265°  under  a  pressure  of  12  mm.  and  is  a  viscous,  yellow  oil 
having  the  density  d  13713°  =  1-1347. 

0-2005  gave  0-5202  00^  and  01220  B^O.     0  =  70-75  ;  H  =  6-75. 
OjgHggO^  requires  0  =  70-75  ;  H  =  6-60  per  cent. 

On  hydrolysis,  this  compound  yields  phenylbenzylglutaconic  acid, 
the  reaction  being  effected  by  digesting  the  ethylic  salt  with  excess  of 
alcoholic  potash  on  the  water-bath  for  6  hours.     The  solid  residue 


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250  RUHEMANN  :   THE  ACTION   OF   AMMONIA  ON 

left  on  diBtilling  ofiE  the  alcohol  is  dissolved  in  water  and  dilate  sul- 
phuric acid  added;  effervescence  takes  place,  and  the  organic  acid 
is  precipitated  as  a  very  viscous  substance  which  does  not  solidify 
even  after  standing  for  some  time  ;  it  readily  dissolves  in  alcohol  and 
in  ether.  Without  further  purification,  it  is  transformed  into  the 
ethylic  salt  by  saturating  its  alcoholic  solution  with  hydrogen  chloride, 
and,  after  24  hours,  adding  water  to  the  solution ;  the  oil  which 
separates  is  then  dissolved  in  ether,  the  ethereal  layer  shaken  with 
sodium  carbonate,  and,  after  removal  of  the  ether,  distilled  under 
diminished  pressure. 

n.Lri^n.        7  7.  s  C^Hg-CrOH-COOCaHg    . 

J)tethyltcphenylbenzylgluiac<maie,  c^H,- CH^  CH- 0000,4    '  "  "" 

yellow  oil  which  boils  at  240 — 241°  under  a  pressure  of  10  mm.  and 
has  the  density  d  13713°=  1 '1082. 

On  analysis,  the  following  numbers  were  obtained. 

0-2037  gave  0-6598  CO,  and  0-1 255  HgO.    0  =  74-94 ;  H  =  6-84. 
O22H24O4  requires  0  =  75-0  j  H  =  6*81  per  cent. 

Monethylic  phenyJhenzylgluiaconate  is  formed  along  with  the  former 
compound,  and  is  extracted  from  the  product  of  etherification  of  the 
acid  by  the  treatment  with  sodium  carbonate.  On  adding  an  excess 
of  hydrochloric  acid  to  the  alkaline  solution,  a  viscous,  yellow  oil  is 
precipitated  which  partially  solidifies  in  the  course  of  a  few  days ; 
the  solid  product  is  collected  with  the  aid  of  the  pump,  washed  with 
very  dilute  spirit,  and  purified  by  recrystallisation  from  the  same 
solvent.     The  colourless  prisms  thus  obtained  melt  at  98° 

The  analytical  data  agree  with  the  formula 

CeHj-CIOH-OOOCaHg  ^^  C^H^- CIOH- COOH 

O^jHg-  CHg-  CH-OOOH  OeHg-  OH,-  CH-  COOC3H5' 

0-2036  gave 05530  00^  and  0-1103  H^O.     C- 7407 ;  H  =  6-02. 
01945     „     0-5280  CO3    „    01095  H^O.     0  =  74-03;  H  =  625. 
C20H20O4  requires  0  =  74-07  ;  H  =  617  per  cent. 

The  neatral  solution  of  the  monethylic  salt  in  ammonia  gives, 
with  silver  nitrate,  a  white  precipitate  of  the  corresponding  stiver 
salt  which  is  not  acted  on  by  light.  It  was  analysed  after  being 
dried  in  a  vacnum. 

0-2335  left,  on  ignition,  0*0585  Ag.     Ag  =  25-05. 

OjoHjgAgO^  requires  Ag  =  25-05  per  cent. 

The  transformation  of  diethylic  phenylbenzylglutaconate  into 
phenylbenzyldihydroxypyridine  takes  place  very  slowly,  5 — 6  days 
heating  with  aqueous  ammonia  in  a  closed  tube  at  150°  being 
required  before  4  grams  of  the  oil  entered  into  solution.     The  con- 


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STHEEEAL  SALTS  OF  OBGANIC  ACIDS.         251 

tents  of  the  tube,  the  ammoniacal  liquor,  and  a  small  qaantitj  of  a 
crystaUine  product  are  freed  from  ammonia  by  heatiug  in  a  vacuum  ; 
hydrochloric  acid  is  then  added  in  excess,  and  the  precipitate  formed 
is  washed  with  water  and  dilute  alcohol.  The  substance  crystallises 
from  hot  alcohol  in  faintly-coloured,  lustrous  plates  which  melt  at 
176°  to  a  brown  liquid. 
The  result  of  analysis  agrees  with  the  formula 

C.H.-0<«l:«i01j>N, 

0-1862  gave  0-5325  OOg  and  0-0937  H^O.     C  =  7799  ;  H  =  560. 

0-2338     „     10-5  c.c.  of  nitrogen  at  19°  and  766  mm.     N  =  5-20. 

CigHigNOj  requires  C«  77-97  ;  B[  =  5-41 ;  N  =  5-05  per  cent. 

With  a  drop  of  ferric  chloride,  the  alcoholic  solution  gives  a  purple 
coloration  which  is  discharged  by  excess  of  the  chloride.  This 
dihydroxypyridine  is  oxidised  under  the  same  conditions  as  the 
others  ;  when  its  solution  in  alcohol  is  boiled,  with  free  access  of  the 
air,  it  first  turns  green,  and  then  brown.  On  adding  silver  nitrate 
to  the  substance  dissolved  in  ammonia,  a  yellow  precipitate  is  formed 
which  darkens  on  warming. 

Farmaticn  ofa-Fyrone  DerivcUivee  and  their  beltaviaur  toioanrda 
Ammoma. 

The  ease  with  which  the  union  of  ethylic  malonate  and  its  homo- 
logues  with  ethereal  salts  of  acids  containing  an  ethylene  or  acetylene 
linking  is  effected  by  sodium  ethoxide  induced  me  to  study  the  action 
between  the  ethereal  salts  of  acids  of  the  acetylene  series  and  those  of 
j9-ketonic  acids.  This  investigation  has  been  undertaken  especially 
with  the  view  of  transforming  the  compounds  which  were  expected  to 
be  produced  in  this  reaction  into  derivatives  of  hydroxypyridine,  but, 
as  mentioned  in  the  introduction,  a-pyrone  compounds  are  formed 
which,  under  the  influence  of  ammonia,  do  not  yield  pyridine  deriva- 
tives. 

Ethylic  a'Pyrone-^^methyl-y-phanyl-P^'carhoxylate. 

The  mixture  of  ethylic  acetoacetate  and  phenylpropiolate  does  not 
evolve  heat  on  the  addition  of  dry  sodium  ethoxide ;  the  union  of  the 
two  ethylic  salts,  however,  may  be  effected  by  digesting  the  mixture 
on  the  water-bath  for  5 — 6  hours,  but,  in  order  to  obtain  a  satisfac- 
toiy  yield  of  the  a-pyrone  compound,  it  is  necessary  to  use  a  larger 
quantity  of  the  ethoxide  (about  2 — 3  grams)  than  in  the  preparation 
of  the  ethylic  salts  of  the  polycarboxylic  acids.     On  treating  the  mix- 


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252  RUHEMANN:   THE   ACTION   OF  AMMONIA   ON 

ture  with  an  excess  of  dilate  sulphuric  acid,  crystals  continue  to  sepa- 
rate for  some  time ;  these  are  collected,  washed  with  dilute  alcohol^ 
and  crystallised  from  hot  alcohol,  from  which  they  are  deposited  as 
long,  colourless  needles  melting  at  104^. 

This  substance  is  comparatively  stable ;  it  passes  over  readily  at 
207 — 214°  under  a  pressure  of  12  mm.  with  but  slight  decomposi- 
tion, as  a  yellowish  oil  which  quickly  solidifies.  The  pyrone  com- 
pound is  insoluble  in  water,  but  dissolves  in  ether  as  well  as  in  alcohol, 
and  these  solutions  do  not  give  a  coloration  with  ferric  chloride. 

The  analytical  data  agree  with  those  required  by  the  formula 

COOCgHg 

0-2013  gave  0-6128  CO^  and  0-1038  HgO.     C  =  69-47 ;  H  =  6-72. 
0-2024     „     0-5165  OO2    „     0-0997  HjO.     0  =  69-69 ;  H  =  5-47. 
Cj^H^^O^  requires  0  =  69-76  ;  H«6-42  per  cent. 

ffydrolysis  of  Eihylie  Methylphenylpf/raneccMrboocylate, — ^The  course 
which  the  hydrolysis  of  the  compound  takes  is  in  accordance  with  the 
above-mentioned  constitution.  The  reaction  is  accompanied  by  decom- 
position of  the  substance,  with  formation  of  phenylglutaconic  and  acetic 

acids,  and  is  to  be  expressed  by  the  equation  ^  _?'  Y*  V]]>0  + 

^  ^  ^  00002H5-C:0(OH3) 

3KH0  =  ^«^^'  9-^^'  ^^^^  +  OHo-  OOOK  +  O^HeO. 
CH2-000K  ^  ^    * 

This  transformation  is  effected  by  alcoholic  potash  ;  on  adding  the 

latter  to  the  ethylic  salt,  a  red  coloration  is  produced  which  disappears 

on  boiling.     After  4  hours  digestion  on  the  water-bath,  the  alcohol  is 

distilled  off,  the  residue  dissolved  in  water,  and  hydrochloric  acid 

added ;   this  precipitates   a  crystalline  solid  readily  soluble  in  hot 

water,  from  which  it  crystallises  in  colourless  prisms.     The  compound 

is   characterised    as   phenylglutaconic  acid    by   the   melting    point, 

164 — 166°,  and  by  the  results  of  analysis. 

0-2035  gave  0-4778  00^  and  0-0895  HgO.    0 « 64-03 ;  H  =  488. 
Oi^HjoO^  requires  0  =  64-07  ;  H  =  4-85  per  cent. 

The  presence  of  acetic  acid  in  the  products  of  hydrolysis  of  the  pyrone 
compound  was  ascertained  by  the  ordinary  tests. 

Action  of  Ammonia  on  Ethylic  Methylphenylpyroneccurboocylate, — ^The 
pyrone  derivative  dissolves  in  absolute  alcoholic  ammonia  if  left  in 
contact  with  it  for  about  an  hour,  and  the  pale  yellow  solution  deposits 
a  white,  crystalline  solid  which  rapidly  increases  in  quantity  ;  this  is 
collected  on  a  filter,  washed  with  absolute  alcohol,  and  dried  in  a 
vacuum  over  sulphuric  acid.     The  following  analysis  indicates  thc^t 

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BrrflERBAL  SALTS   OF  ORGANIC  ACIDS.  263 

the  pjrone  compound  has  undergone  a  transformation  which  may 
be  represented  by  the  equation 

CeH^-CICH-CO^^^     2 ^^  ^         CeHg-CICH-  COONH, 
COOCjHs-CiqCHg)"'^  "    COOC2H^-C:C(CH3)NH,   ' 

0-2044  gave  0-4606  CO,  and  0-1253  HjO.     0  =  6145  ;  H-6-81. 
0-2025     „     0-4560  CO,    „    0-1265  H3O.     C  =  61-41 ;  H  =  6-94. 
0-2458     ,,     20  c.c.  of  nitrogen  at  15°  and  766  mm.     N  =  9'60. 
CijHjoNjO^  requires  0  =  6 1  64  ;  H  =  684  ;  N  =  959  per  cent. 

The  compound  thus  produced  is  very  soluble  in  water,  and  on  heating 
at  100*",  it  evolves  ammonia  and  turns  yellow.  It  is  characterised 
as  an  ammonium  salt  by  the  fact  that,  with  silver  nitrate,  its  aqueous 
solution  yields  a  white,  gelatinous  precipitate  of  the  corresponding 
silver  salt ;  this  is  not  acted  on  by  light,  and  although  it  turns  brown 
when  heated  at  100°,  it  can  be  dried  in  a  vacuum. 

0-2725  left,  on  ignition,  0-0767  Ag.     Ag  =  28-14. 
0-4090  gave  14  c.c.  of  nitrogen  at  18°  and  750  mm.    N  =  3-89. 
Oi5H:igAgN04  requires  Ag  =  2827 ;  N  =  3*66  per  cent. 

On  adding  hydrochloric  acid  to  the  aqueous  solution  of  the  ammo- 
nium salt,  a  substance  is  formed  which  is  not  the  expected  pyridine 
derivative,  but  is  ethylic  methylphenylpyronecarboxylate.  The  acid, 
therefore,  removes  2  mols.  of  ammonia  from  the  ammonium  salt  and 
transfers  it  into  the  same  pyrone  compound  from  which,  by  the  addition 
of  ammonia,  it  was  produced. 


Ethylic  a-Pyrone-ay-diphenyl-pt'Carhoxylate. 

This  is  produced  in  the  same  manner  as  the  former  compound,  by 
digesting  a  mixture  of  ethylic  phenylpropiolate  and  benzoylacetate 
with  sodium  ethoxide  on  the  water-bath  for  several  hours,  using  in 
this  case  also  about  2 — 3  grams  of  the  ethoxide.  The  reaction  is 
generally  incomplete,  a  certain  amount  of  the  ethereal  salts  remaining 
unoombined;  their  presence  often  prevents  the  pyrone  compound 
from  crystallising  out  of  the  mixture,  but  the  separation  can  easily  be 
effected  by  fractionally  distilling,  under  diminished  pressure,  the  oil 
obtained  on  adding  dilute  sulphuric  acid  to  the  product  of  the  reaction. 
First,  the  unchanged  ethylic  salts  pass  over,  and  then,  at  about  270°, 
under  a  pressure  .of  12  mm.,  the  pyrone  derivative  distils  as  a  very 
viscous,  yellowish  oil  with  green  fluorescence.  This  oil,  after  a 
short  time,  solidifies ;  the  solid  readily  dissolves  in  ether  or  alcohol, 
and  crystallises  from  the  latter  in  well-developed,  colourless  prisma 
which  melt  at  120—121°. 

yOL.  LXXV  S 

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254>  WA.de  :  THE  CHANQES   OF   VOLUME   DUE   TO 


The  analytical  results  correspond  with  those  required  by  the  formula 

C00CaH5-C:C(CgHjjy 

0-2021  gave  05553  00^  and  00910  H^O.     C  «  74-94 ;  H  =  500. 
CjoHjgO^  requires  C  =  75*0 ;  H  =  50  per  cent. 

The  yield  of  the  pyrone  compound  is  very  satisfactory,  as  the 
unaltered  ethylic  salts  which  are  contained  in  the  lower  fraction  of 
the  oil  can  be  transformed  into  the  pyrone  by  repeated  digestion  with 
sodium  ethoxide. 

The  further  investigation  of  the  pyrone  derivatives  described  in 
this  paper,  and  the  study  of  the  reactions  between  ethylic  salts  of 
other  )3-ketonic  acids  and  those  of  unsaturated  acids  of  the  acetylene 
series,  is  in  progress,  and  will  be  published  shortly. 

GONVILLB  AND  CaIUB  CoLLEOS, 

Cambbibob. 


XXVIII. — The  Changes  of  Volume  due   to  Dilution  of 
Aqueous  Solutions. 

By  Edwaed  Brucb  Herschel  Wadb,  M.A. 

Object  of  the  Paper. 

The  object  of  this  paper  is,  first,  to  describe  an  apparatus  intended 
for  the  study  of  volume  changes  consequent  on  diluting  an  aqueous 
solution  ;  secondly,  to  give  an  account  of  experiments  performed  with 
that  apparatus.  The  experimental  numbers  obtained  are  not  intended 
merely  as  illustrations  of  the  applicability  of  the  method  (though  they 
serve  that  purpose),  but  also  as  accurate  values  of  the  change  of 
volume  on  dilution.  The  actual  change  studied  in  this  paper  is  that 
which  occurs  when  a  certain  volume  of  solution  is  diluted  with  <m 
equal  volume  of  tvcUer, 

I.  Review  of  Previous  Work  hearing  on  ike  Suhfect, 

The  method  of  attacking  the  problem  hitherto  invariably  employed 
has  been  to  determine  the  density  of  solutions ;  and  the  researches 
carried  out  may  be  profitably  subdivided  into  two  classes,  (a),  those 
the  direct  object  of  which  is  the  measurement  of  the  contraction  on 


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DILUTION  OF  AQUEOtTS  SOLtTTIONS.  255 

dilutioii,  (h),  those  in  which  the  density  was  observed  for  ordinary 
purposes. 

Researches  hearing  directly  on  the  subject  of  Contraction, — ^The  first 
group  includes  the  work  of  Nicol  {Fhil.  Mag,,  1883,  [v],  16,  121), 
Oharpy  {Compt.  rend.,  1889,  109,  299),  and  others.  Nicol's  plan  was 
to  determine  the  density  of  a  solution  of  known  strength,  and  then 
to  dilute  to  exactly  half  that  strength,  and  redetermine  the  density. 
His  paper  contains  a  table  of  contractions  obtained  in  this  way. 
Charpy's  densities  are  carried  out  to  four  places  of  decimals,  so  that 
changes  of  volume  less  than  1  in  10,000  would  escape  notice. 
Marignac  {Arch,  Gen,,  1870,  39,  273)  made  observations  of  density  to 
five  places  of  decimals,  in  order  to  find  the  relation,  if  any,  of  con- 
traction to  heat  capacity. 

Other  Researchesibearing  on  the  Subject. — Determinations  of  density 
for  various  purposes  have  been  made  by  many  observers,  but  it  will 
not  be  necessary  to  refer  to  those  which  are  quoted  to  less  than  five 
places  of  decimals.  Amongst  those  to  be  noticed  are  the  results  of 
Ctorlach  {Zeit.  anal.  Chem.,  8,  279),  Marignac,  Nicol,  Pickering  (Trans., 
1891),  Bremer  {Zeit.  j^ysikal,  Chem,,  1888,  3,  423),  Kohlrausch  and 
Hallwachs  (Ann,  Phys,  Chem,,  1893,  50,  118 ;  1894, 63, 15),  and,  later, 
Kohlrausch  {ibid,,  1895,  61,  185). 

Eocamination  of  escisting  Density  Determinations, — In  most  of  the 
cases  quoted,  the  first  obstacle  to  the  employment  of  the  densities  in  the 
study  of  contractions  is  the  way  in  which  the  results  are  stated.  To 
calculate  the  contraction  due  to  dilution  from  the  data  in  an  ordinary 
table  of  densities  is  a  very  serious  task.  Of  course  an  actual  error  in 
arithmetic  would  not  be  excusable,  but  most  of  the  tables  of  density 
are  so  constructed  that  one  must  have  recourse  to  much  interpolation 
in  order  to  obtain  the  desired  result.  Again,  when  the  very  incon- 
venient calculation  has  been  made,  the  results  obtained  by  different 
authorities  are  not  very  concordant ;  as  an  example,  Table  I  (p.  256) 
gives  the  contractions  of  certain  solutions  as  deduced  from  the  tables 
of  Nicol,  Pickering,  Marignac,  and  Kohlrausch  and  Hallwachs.  The 
last  two  observers  have  utilised  earlier  observations  by  Gerlach 
and  Kohlrausch  to  complete  their  tables. 

Explanation  of  TahU  I. — »=  gram  equivalents  per  litre  before  dilu- 
tion ;  n/2  =  gram  equivalents  per  litre  after  dilution ;  F=>  volume 
which  holds  1  gram  equivalent  before;  2 F=  volume  which  holds 
1  gram  equivalent  after  dilution.  The  figure  in  the  remainiug 
columns  are  the  contractions  in  c.c.  per  100,000  of  the  diluted 
solution  as  deduced  from  the  following  authorities.  Nicol  (N^)  and 
(Nj) ;  Kohlrausch  and  Hallwachs  (K.  and  H.)  ;  Pickering  (P) ;  Marig- 
nac (M)  (/oe.  cit,). 

The  discordance  amongst  the  various  authorities  is  perhaps  not 

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256 


wade:  the  changes  of  volume  dub  to 


Table  I. 
Sodium  chloride. 


n. 

n/2. 

r. 

2V. 

JVi. 

JVi. 

K. 

M. 

1 

0-6 

1000 

2000 

81-5 

82-5 

15 

0-8 

0-4 

1250 

2500 

22-4 

24-4 

8 

0-6 

0-3 

1666 

8333 

141 

14-7 

8-8 

0-66 

0-276 

16 

,,, 

... 

... 

0-4 

0-2 

2500 

5000 

6-2 

7-2 

1-0 

0-275 

0-185 

1 

... 

... 

0-2 

0-1 

5000 

10000 

... 

2-8 

Sulphuric  acid. 


Cane-sugar. 


n. 

n/2. 

V. 

2r. 

K. 

if. 

P. 

1 

0-5 

1000 

2000 

85-5 

34*5 

27 

0-8 

0-4 

1250 

2500 

29-6 

20-8 

24-8 

0-6 

0-3 

1666 

8883 

23  1 

13-5 

20-7 

0-4 

0-2 

2500 

5000 

17-2 

5-4 

15-6 

n. 

n/2. 

F. 

2F. 

1 

0-5 

1000 

2000 

35-0 

62 

0-8 

0-4 

1250 

2500 

800 

82-8 

0-6 

0'3 

1666 

8833 

180 

9-3 

0-4 

0-2 

2500 

5000 

9-8 

0 

surprising  if  we  remember  that  to  establish  one  value  of  the  contrac- 
tion by  measurements  of  density  involves  the  errors  of  four  weighings, 
namely,  (1)  pyknometer  empty,  (2)  full  of  water,  (3)  full  of  solution, 
(4)  full  of  diluted  solution.  Neglecting  further  errors  of  temperature 
and  concentration,  the  sum  may  very  easily  surpass  one  in  100,000. 
With  regard  to  Kohlrausch  and  Hallwachs*  method  of  determining 
the  density,  which  claims  a  very  high  order  of  accuracy,  it  should  be 
said  that  it  is  restricted  to  solutions  whose  density  is  below  1  -03,  so 
that,  for  stronger  solutions,  they  have  adopted  numbers  obtained  by 
less  refined  methods. 


II.  The  Experimental  Method  employed  in  the  Paper, 

Features  of  ike  Meikod, — The  method  employed  will  now  be  explained 
without  dwelling  as  yet  on  details  of  procedure.  The  contraction  of 
a  solution  on  dilution  with  an  equal  volume  of  water  is  observed  direct^ 


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DILUTION  OF  AQUEOUS  SOLUTIONS. 


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^^ 


Aa 


c 


^ 


in  an  apparatus  constructed  specially  for  that  purpose.     Attention  is 

fixed   on   the  contraction,  and  no  attempt  is  made  to  measure  the 

absolute  volumes  very  accurately.     In  order,  however,  to  make  the 

results  obtained  with  different  pieces  of  apparatus  comparable  and  of 

general  utility,  the  results  are  stated,  not  as  actual  contractions,  but 

as  contractions  per  100,000  c.c.  of  the  diluted  solution,  and  for  this 

reason  some  knowledge  of  the  actual 

volumes  mixed  is,  of  course,  necessary.  Fio.  1. 

It  will  be  shown,  however,  that  a  very 

imperfect  knowledge  of  the  absolute 

volumes  suffices  for  this  purpose. 

Descriptums    of    the    Apparatus. —  ^^      ||l|.~         \'i) 

Roughly,  the  apparatus  resembles  a 
U-tube  whose  two  limbs  are  extended 
into  bulbs  of  nearly  equal  capacity, 
BB',  Fig.  1.  These  bulbs  are  provided 
with  long  capillary  stems,  CO',  between 
which  a  scale  is  placed ;  a  few  cubic 
centimetres  of  mercury,  H,  fill  the 
bend  of  the  tube.  Thus  the  contents 
of  the  bulbs  are  isolated,  as  by  a  door. 
It  was  possible,  as  will  be  seen,  to  fill 
one  bulb  and  stem  with  a  solution, 
and  the  other  with  water.  During 
the  filling,  the  water  and  solution  are 

kept  entirely  separate  by  the  partition     D    ~  D' 

of  mercury.  To  obtain  a  measure  of 
the  contraction  due  to  mixing  the 
water  and  solution,  it  is  necessary  first 
to  set  the  apparatus  upright  in  a 
water-bath  and  read  the  position  of 
the  menisci  of  water  and  solution  on 
the  capillaries;  then  to  place  the 
apparatus  in  a  horizontal  position,  so 
that  [the  mercury  barrier  no  longer 
intervenes  and  diffusion  takes  place, 

which  may  be    promoted  by   slight  

shaking  of   the  mercury;  lastly,    to 

set  the  apparatus  upright  once  more  and  take  a  second  reading  of  the 
menisci  in  the  capillaries.  The  difference  of  the  first  and  second 
readings  is  a  measure  of  the  contraction  due  to  mixing. 

Accessory  Apparatus. — Besides  the  actual  contraction  apparatus,  the 
outfit  consists  of  a  water-bath,  stirring-gear,  reading  telescope  and 
mercurial  thermometer.     The  water-bath  was  a  galvanised  iron  tank 

_. ,  ^oogie 


258  WADE:  THE  CHANGES  OF  VOLUME  DUE  TO 

holding  50  gallons,  and  the  natural  fluctuations  of  this  large  mass  were 
exceedingly  slow,  so  that  it  was  easy  to  keep  the  water  at  constant 
temperature  by  placing  a  small  gas  jet  under  the  tank  and  adjusting 
the  height  of  the  flame  when  necessary  ;  for  such  a  large  water-bath 
an  automatic  thermostat  is  quite  superfluous.  The  stirring-gear 
consisted  of  two  propellers  driven  by  a  large  water  motor ;  for  the 
construction  of  this  very  efficient  apparatus,  I  have  to  thank  Mr.  F. 
Thomas,  of  Jesus  Lane,  Cambridge,  who  has  had  much  experience 
in  similar  work.  The  thermometer  was  by  Kicks,  and  gave  actual 
elevations  correct  to  0*1°  and,  what  was  much  more  important,  could 
be  trusted  to  indicate  differences  of  temperature  in  the  water-bath  to 
within  about  0-005°. 


III.  ThA  Conduct  of  an  Experiment, 

Filling  ths  Apparatus, — At  the  outset  of  an  experiment,  the 
apparatus  has  to  be  filled  with  water  on  one  side  and  solution  on  the 
other.  Some  distilled  water  is  well  boiled  to  free  it  from  air,  and  this 
water  is  drawn  into  the  apparatus  while  hot ;  to  do  this,  one  mouthy 
C,  Fig.  2,  of  the  apparatus  is  connected  with  the  hot  water  in  the 
funnel  A.  By  alternately  gently  sucking  and  blowing  at  B,  we  can 
gradually  fill  one  bulb  with  water  free  from  air,  without  allowing  it 
ever  to  transgress  the  partition  of  mercury.  In  exactly  the  same  way, 
the  remaining  bulb  can  be  filled  with  hot,  boiled-out  solution. 
Throughout  the  operation,  the  mercury  separates  water  and  solution. 
When  the  liquids  are  cool,  the  filling  has  to  be  completed,  and  pains 
must  be  taken  that  when  the  apparatus  is  vertical  the  two  mercury 
surfaces  are  in  the  same  horizontal  plane,  otherwise  the  ratio  of  the 
volumes  of  the  liquids  in  the  two  bulbs  will  not  be  a  definite  one. 
The  operation  is  referred  to  as  ''  levelling." 

Levelling. — ^This  could  be  accomplished  with  the  necessary  accuracy 
by  placing  the  apparatus  vertically  in  a  shallow  glass  trough,  T,  con- 
taining water.  The  water  is  removed  by  degrees,  and  if  the  observer 
looks  upward  obliquely,  see  Fig.  2,  at  the  surface  of  the  water,  he  sees 
the  reflections  of  the  mercury  menisci  descending  to  meet  the  real  ones 
as  the  water  is  removed.  If  the  two  mercury  menisci  are  in  one 
horizontal  plane,  they  will  come  in  contact  with  their  reflections  at 
the  same  moment ;  if  they  fail  to  do  so,  water  is  added  to  one  bulb,  or 
solution  to  the  other,  until  the  test  is  satisfied.  The  test  was  sensitive 
enough  to  show  a  change  of  0  05  c.c.  in  either  bulb,  which  was  many 
times  smaller  than  what  was  absolutely  necessary. 

Readings. — We  have  next  to  obtain  accurate  readings  of  the  menisci' 
on  the  scale  of  the  capillaries.  The  menisci  are  brought  into  such  a 
position  that  the  horizontal  cross-wire  of  the  telescope  appears  to  pass 

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through  them  both,  while  the  vertical  cross-wire  grazes  the  image  of 
the  scale ;  the  reading  where  the  horizontal  cross-wire  intersects  the 
scale  is  then  recorded.  To  ensure  accurate  readings,  we  must  observe 
the  following  precautions.  1. — The  temperature  of  the  water-bath 
must  be  kept  steady,  or  else  fluctuations  must  be  allowed  for,  and  kept 
within  0'02°.  2.— The  apparatus  must  be  exposed  for  a  sufficient 
period  to  this  temperature.     3. — Parallax  must  be  avoided.     With 

Fio.  2. 


regard  to  the  temperature,  it  could  be  read  with  relative  accuracy  to 
about  0'005^y  and  owing  to  the  large  capacity  of  the  bath  it  was 
usually  constant  to  within  about  0*02^  for  a  whole  day.* 

To  ensure  that  the  apparatus  had  been  exposed  to  this  steady  tem- 
perature for  a  sufficient  period,  readings  were  always  continued  until 
they  became  steady.     With  the  very  vigorous  stirring  employed,  the 

*  This  is  illustrated  in  Tables  V  and  VII  (pp.  264  and  266),  which  might  be 
multiplied,  and  is  of  the  greatest  importance.  The  limit  of  accuracy  is  ultimately 
fixed  by  the  steadiness  of  the  water-bath. 

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260       WADE:  THE  CHANGES  OF  VOLUME  DUE  TO 

steady  state  tisually  sets  in  in  about  three-quarters  of  an  hour,  and 
then  no  further  changes  can  be  detected  for  six  hours,  except  such  as 
correspond  accurately  with  the  small  and  slow  changes  of  the  water- 
bath  temperature.  This  point  being  settled  in  preliminary  experi- 
ments, the  apparatus  was  assumed  to  be  in  the  steady  state  when  its 
readings  were  unchanged  during  an  hour  and  a  half.  Parallax  was 
avoided  by  setting  the  capillaries  vertical,  and  using  a  spirit  level  on 
the  reading  telescope. 

TJm  Miaoing  qf  Water  and  Solution. — When  the  reading  thus 
obtained  has  been  entered  in  the  notebook,  short  lengths  of  rubber 
tubing  of  narrow  bore  are  slipped  over  the  ends  of  the  capillaries,  and 
into  these  tubes  are  placed  drawn-out  pieces  of  glass  tubing.  The  tips 
of  the  glass  tubes  are  now  sealed,  and  the  apparatus  is  ready  for  the 
process  of  mixing.  The  best  way  to  secure  complete  mixing  of  water 
and  solution  was  found  by  preliminary  experiments  with  coloured 
solutions,  so  that  every  stage  could  be  watched.  The  apparatus  is  set 
horizontally  with  the  bulb  containing  the  salt  solution  uppermost. 
The  denser  solution  descends  owing  to  gravity,  and  almost  without 
diffusion,  so  that  two  layers,  one  of  water  and  the  other  of  solution, 
can  be  distinguished  in  each  bulb.  A.  slight  shake  of  the  mercury  at 
this  stage  makes  the  mixing  almost  complete.  The  mereury  is  then 
transferred  about  50  times  from  one  bulb  to  the  other,  a  slight 
shaking  following  each  transfer.  Further  mixing  will  then  not  alter 
the  reading  obtained,  and  analysis  shows  that  the  concentration  of  the 
two  bulbs  is  the  same.     (See  section  YI.) 

Second  Reccing. — ^The  reading,  after  mixing,  is  taken  in  just  the  same 
way  as  the  first,  the  sealed  ends  of  the  glass  tubes  mentioned  above 
being  first  cut  off.  The  difference  of  the  readings  on  the  capillaries 
before  and  after  mixing  measures  the  contraction. 

Determination  qf  Concentration. — ^The  concentration  was  in  almost 
all  cases  found  analytically  in  preference  to  working  with  synthetically 
prepared  solutions;  the  objection  to  the  latter  course  was  that  it 
would  be  necessary  to  dry  out  the  apparatus  before  each  experiment. 
The  carbamide  solutions,  however,  were  made  up  to  definite  strength 
and  the  apparatus  carefully  dried,  instead  of  using  an  analytical 
method.  The  chlorides  were  all  titrated  with  silver  nitrate,  and  the 
oxalic  acid  and  potassium  ferrocyanide  by  potassium  permanganate. 
The  strength  of  sugar  solutions  was  found  from  their  specific  gravities 
with  the  help  of  Kohlrausch  and  Hallwachs'  tables. 

lY.     Standardisation  of  Appa/ratus  and  Sclutione. 

Th9  section  devoted  to  the  redaction  of  experiments  (VI)  will  show 
that  tha  necessary  data  are,  (1)  the  voluine  of  that  part  of  the  appa* 

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261 


ratufi  unoccupied  by  mercury,  (2)  the  volume  of  a  portion  of  the 
capillariee  equal  in  length  to  one  scale  division ;  from  these,  a  factor 
(called  the  apparatus  constant)  can  be  obtained  which,  multiplied  into 
the  observed  difEerence  of  the  first  and  second  readings,  gives  the  con- 
traction in  cubic  centimetres  per  100,000.*  Besides  this  constant,  we 
need  to  know  the  temperature  coefficient  of  the  apparatus,  that  is,  the 
amount  by  which  the  reading  of  the  apparatus  is  affected  by  a  change 
of  1*0°  and  also  a  constant  (called  the  inequality  constant)  which  is 
deiined  as  the  difference  in  volume  of  the  two  bulbs  divided  by  their 
sum.     The  significance  of  this  constant  is  explained  in  section  TI. 

Determination  qf  the  Volumes  qf  the  Bulbs, — ^This  was  generally  done 
by  weighing  the  apparatus,  first  empty,  then  after  the  admission  of  the 
mercurial  partition,  and  again  after  filling  the  remaining  space  with 
water.  As  a  control  method,  the  volume  of  water  required  to  fill  the 
space  unoccupied  by  mercury  was  drawn  in  from  a  calibrated  burette, 
and  as  another  control  the  same  space  was  completely  filled  with  deci- 
normal  sodium  chloride,  which  was  then  washed  out,  by  repeated 
washings,  into  a  beaker  and  titrated  with  decinormal  silver  nitrate ; 
the  volume  of  silver  nitrate  required  is  equal  to  the  volume  of  liquid 
(other  than  mercury)  which  is  contained  by  the  apparatus.  The  two 
control  methods  were  very  useful,  as  after  the  apparatus  was  once 
mounted  in  its  stand,  it  could  not  be  conveniently  displaced  for 
weighing.  The  capillaries  were  standardised  in  the  usual  way  by 
weighing  columns  of  mercury  occupying  the  greater  part  of  their  length 
and  calculating  their  mean  cross-section.  The  local  cross-section  was 
found  by  calibration  with  short  columns  of  mercury.  A  preliminary 
calibration  was  always  made,  and  if  unsatisfactory  the  tube  in  question 

Tablb  II. 


No. 

Apparatus  constant. 

Notes. 

1 
2 

2a 
8 

4 

A.  1. 

12-95 

2-69 

4-58 

17-91 

10-77 

17-46 

(10-88  in  experiments  previous  to  October 
16th,  1897,  owing  to  use  of  a  larger 
mercury  partition. ) 

Broken  after  only  six  experiments  had  been 
made. 

*  The  formula  for  this  constant  is  100,000  (;ir+ mi)/ ^a,  where  fir  is  the  mass  of 
mercury  in  length  of  right  capillary  equal  to  one  mean  scale  unit,  /ii  the  same  for 
left  capillary,  p  density  of  mercury.  F  the  volume  of  the  apparatus  exclusive  of 
that  occupied  by  mercury  partition.  ^  . 

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WADE:  THE  CHANGES  OF  VOLUME  DUE  TO 


was  rejected.  All  these  standardisings  were  repeated  at  intervalB 
throughout  the  research,  and  a  complete  history  of  each  apparatus  was 
kept.  Table  II  (p.  261)  gives  the  constants  of  the  pieces  of  apparatus 
used. 

The  temperature  coefficient  of  each  apparatus  was  determined  over 
a  range  of  about  10°  by  reading  the  levels  of  the  menisci  at  various 
steady  temperatures.    The  following  table  will  serve  as  an  example. 

Table  III. 
Temp,  coeff.  qf  Tan.  3. 


Temp. 

Beading. 

19-66' 
19-66 
19-66 

104-260 
104-260. 
104-260 

19-66 

104-260 

19-98^ 
19-96  Y 
19-97  j 

104-726 

104-71 

104-716 

19-97 

104-72 

TJierrfore,  change  qf  reading  far  0-or= 0-012. 


16-60** 
20-17 


101-276 
106-606 


Therefore,  change  qf  reading  for  0-01'*= 0-012. 

The  inequality  constant  d  was  found  by  measuring  the  volume  of 
each  bulb  separately  in  the  way  already  described,  and  also  by  filling 
one  bulb  with  a  solution  of  sodium  chloride  and  the  other  with  water 
and  mixing  as  in  an  ordinary  experiment ;  the  loss  in  titre  due  to 
mixing  gives  a  value  of  the  inequality.  The  value  of  d  can  also  be 
controlled  by  making  a  series  of  observations  of  contraction  with 
the  solution  first  in  the  right  bulb ;  secondly,  in  the  left.  If  the 
proper  value  of  d  is  used  in  the  reduction  of  these  results,  the  two 
curves  will  be  identical  (see  YI.). 

Standardising  the  Volumetric  Solutions. — ^The  silver  solution  was 
prepared  (1)  by  weighing  the  pure  silver  nitrate  after  exposure  for 
10  minutes  to  a  temperature  of  120^,  (2)  by  titrating  against 
ammonium  chloride  specially  resublimed  just  before  use,  (3)  by 
weighing  the  silver  chloride  corresponding  to  a  known  mass  of  the 
solution,  (4)  by  titrating  with  specially  purified  potassium  bromide. 

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The  titrations  for  standardising  were  made  both  by  weighing  out  the 
solntions,  and  also  by  using  pipettes  and  burettes,  the  errors  of  which 
were  accurately  known.  The  permanganate  solution  was  standardised 
by  titration  with  oxalic  acid  and  ammonium  oxalate.  When  titrating 
the  solutions  of  potassium  ferrocyanide,  the  permanganate  was 
standardised  by  means  of  a  carefully  recrystallised  specimen  of  that 
substance. 

Y.  CcUcfdation  qf  the  BesulU, 

The  calculation  of  the  results  is,   on  the  whole,   simple.      An 
example  follows  which  it  is  hoped  will  make  it  clear. 


Tablb  IV. 
Sodium  chloride. 


L 

II. 

III. 

IV. 

V. 

VI. 

VIL 

VITL 

108-770 

108-620 

0160'* 

IQ-DSO** 

19-960'* 

0-020" 

0-126 

2-26 

IX. 

X. 

XI. 

XII. 

a. 

5. 

e. 

d. 

10-66 

10-70 

11-28 

10-70 

1-2 

17-91 

0-050 

0-060 

Column  I  gives  the  reading  on  the  scale  of  the  capillaries  before 
mixing.  Column  II,  the  same  after  mixing.  Column  III,  the 
difference.  Column  IV,  the  temperature  of  the  water-bath  at  the 
time  of  recording  reading  in  column  I.  Column  V,  the  same  for 
column  n.  Column  VI,  the  difference  (V-IV).  Column  VII 
shows  the  number  in  column  III  corrected  for  change  of  tempera- 
ture, to  do  which  the  number  in  column  VI  is  multiplied  by  the 
eonstant  a,  and  added  to  the  number  in  oolumn  III.  Column  VIII 
shows  the  contraction  in  cubic  centimetres  per  100,000  ;  numbers  in 
this  oolumn  are  obtained  by  multiplying  those  in  column  VII  by  the 
constant  L  Column  IX  contains  the  volume  of  standard  solution 
measured  from  a  burette  in  order  to  titrate  10  c.c.  (nominal)  of  the 
solution  whose  contraction  is  found  in  column  VIII.  Column  X 
shows  this  volume  corrected  for  calibration  of  the  burette,  and 
oolumn  XI  reduces  it  to  gram  equivalents  per  100,000  c.c.  of  solu- 
tion. To  obtain  column  XI  multiply  the  figures  in  column  X  by 
constant  1  +  c.  Finally,  column  XII  corrects  for  the  inequality  of 
the  two  bulbs.  To  obtain  it,  multiply  column  XI  by  l+d  if  the 
solution  is  in  the  right  bulb,  and  divide  by  l+dii  in  the  left. 

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WADE:  THE  CHANGES  OF  VOLUME  DUE  TO 


VI.  Discussion  of  Errors, 

The  errors  attending  each  operation  will  be  considered  separately, 
and  then  the  question  of  concordance  of  results  will  be  raised. 

Possible  Change  of  Volume  qf  the  Apparatus. — ^A  characteristic 
error  in  most  volumetric  work  arises  from  changes  in  the  volume  of 
the  measuring  apparatus.  In  the  method  described,  all  the  opera- 
tions can  be  carried  out  in  a  water-bath  at  constant  temperature, 
and,  moreover,  a  change  of  volume,  even  if  it  occurs,  is  only  significant 
when  it  takes  place  between  the  initial  and  final  readings.  It  is  to 
be  particularly  noted  that,  as  the  apparatus  is  continually  under 
observation  during  this  interval,  such  a  change  could  scarcely  escape 
detection,  and  a  long  experience  of  the  apparatus  has  not  revealed 
any  such  change  in  the  course  of  an  experiment.  If,  however,  a  change 
occurred  at  the  time  of  mixing,  it  could  not  be  detected  in  the  way 
described,  and,  therefore,  to  test  the  point,  blank  observations  were 
made  with  water  in  each  bulb.  The  example  given  shows  that  no 
change  took  place  in  the  volume  of  the  water,  even  when  the 
apparatus  was  removed  from  the  bath,  and  although  the  mixing  was 
carried  out  much  more  energetically  than  in  an  ordinary  experiment. 


Table  V. 
BlamJc  experimerU  ;  water  in  each  bulb. 


Time. 

Temp. 

Reading. 

Beading  reduced  to 
temp.  19-960^ 

•    1  2-80 

2  6-30 

19-970° 
19-960 

104-716 
104-690 

104-703 
104-702 

Between  1  and  2,  the  apparatus  was  removed  and  mixing  carried  oat 

The  difference  in  the  last  column  is  decidedly  smaller  than  could 
be  read  with  certainty,  and  corresponds  to  a  change  of  only  about 
0-02  in  100,000. 

Errors  in  Standardising. — Even  great  carelessness  in  standardising 
would  scarcely  affect  the  results,  because  the  percentage  error  in  the 
contraction  is  necessarily  equal  to  the  percentage  error  in  the 
standardising  by  which  it  was  deduced.  The  greatest  contractions 
observed  were,  with  very  few  exceptions,  of  the  order  of  40  units, 
that  is,  iO  C.C.  in  100,000  of  the  solution.  An  error  of  1  per  cent,  in 
standardising  would,  therefore,  cause  an  error  of  0-4  such  units,  a 
quantity  at  most  three  or  four  times  greater  than  the  least  which  could 
be  detected  with  certainty,  and  the  error  would  be  correspondingly  less 

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in  smaller  contractions.  But  it  is  altogether  unlikely  that  the  errors 
in  standardising  would  amount  to  1  per  cent.,  as  the  independent 
determinations  of  the  volume  of  the  apparatus  agree  to  within  about 
0*3  per  cent.,  and  the  standardising  of  the  capillaries  are  more  con- 
cordant than  that.  An  example,  taken  from  the  standardising  of 
Ton.  4,  will  illustrate  this. 

Table  VI. 

Standardisation  of  Ton,  4. 


Date. 

F, 

^H, 

Total 
calc. 

Total 
obs. 

Mr. 

Ml. 

February  17  

90-7 
91-4 

7-4 

6-4 
6-5 

98  1 
97-9 

98-0 

98  1 
98-2 
98-0 

0-0630 
0  06821 
0-06290 
0-06806 

„        20  

March      16  

0  07076 

„           25  

007082 

„           26  

0-07067 

V  is  the  •*  water  volume "  or  part  unoccupied  by  mercury,  Vg  the 
"  mercury  volume  "  or  part  occupied  by  mercury.  The  sum  of  these 
gives  the  whole  volume  (total  calc.)  ;  this  total  may  also  be  obtained 
by  direct  observation  (total  obs.).  These  totals  ought  to  be  constant 
to  within  the  error  of  observation,  but  V  and  V^  are  not  necessarily 
the  same  in  different  fillings.  After  March  25,  pains  were  taken  to 
make  Vg  always  equal  to  6*5,  otherwise  the  factor  of  the  apparatus  has 
to  be  recalculated  at  every  filling ;  /ir  and  /a;  are  the  masses  of  mercury 
in  a  mean  scale  unit  of  the  right  and  left  capillaries  respectively. 

The  numbers  in  Table  TI  show  that  the  errors  due  to  standardising 
must  be  small,  and  the  same  conclusion  may  be  drawn  from  the 
regularity  of  the  results  obtained  in  different  appeiratus.  See 
Tables  X,  XI. 

FarcUlactie  Error* — ^This  error  is  also  insignificant.  Thus  ex- 
perience showed  that  if  the  telescope  were  put  out  of  adjustment 
by  a  considerable  distance,  and  the  readings  repeated,  no  sensible 
change  was  produced. 

Incomplete  Mixing, — A  possible  source  of  error,  and  one  which 
undoubtedly  was  present  in  the  preliminary  experiments,  is  imperfect 
mixing ;  in  all  the  final  experiments,  however,  mixing  was  very 
thorough,  and  proved  to  be  complete  by  analysis.  In  the  example 
given  below,  a  reading  was  taken,  the  contents  of  the  apparatus  were 
then  mixed  as  in  an  average  final  experiment,  and  a  second  reading 
was  taken  3  then  a  second  very  thorough  mixing  followed,  and  a 
third  reading  was  taken.  The  second  and  third  readings,  reduced  to 
a  common  temperature,  are  in  agreement,  showing  that  the  first 
piixing  was  complete. 


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266 


WADE:  THE  CHANGES  OF  VOLUME  DUE  TO 


Tablb  VII. 
To  iUustrate  completeness  qf  mixing. 


Time. 

Temp. 

Reading  reduced  to  temp. 
20-385* 

10 
3  0 
6-0 

28  00 
22-32 
22-81 

20-340' 
mixed  aa  in 
20-335 
mixed  again 
20-830 

22-99 
ordinary  final  experiment. 

22-82 
as  before. 

22-82 

The  error  of  inequality  of  tJie  hvJhs  appears  to  be  completely  avoided  by 
the  method  of  correction  described  in  Y,  which  consists  in  increasing  all 
the  values  of  concentration  in  a  certain  ratio  when  the  solution  is  in  the 
smaller  bulb,  and  diminishing  them  when  it  is  in  the  greater.  Great 
attention  must  be  given,  however,  to  the  operation  described  as 
levelling  (page  258),  otherwise  the  ratio  of  the  bulbs  is  not  the  same 
for  the  same  apparatus  in  different  experiments.  The  method  of 
correcting  was  arrived  at  from  a  study  of  Kohlrausch's  tables  of 
density,  which  lead  to  the  conclusion  that  if,  say,  V-  8  cubic  centi- 
metres of  normal  sodium  chloride  are  mixed  with  F+  S  of  water,  the 
contraction  is  sensibly  the  same  as  if  equal  quantities  of  the  two  were 
mixed  (provided  8  is  small),  the  small  deficiency  of  salt  solution  being 
almost  exactly  compensated  for  (as  far  as  contraction  is  concerned)  by 
the  small  excess  of  water.  But  the  final  concentration  will,  in  one 
case,  be  below  half  normal,  and  in  the  other  exactly  half  normal,  for 
both  the  deficiency  of  solution  and  excess  of  water  act  the  same  waj 
on  the  final  concentration.  Hence  the  method  of  correction.  The 
concordance  of  results  by  different  pieces  of  apparatus  with  different 
inequalities,  and  using  opposite  bulbs  to  contain  the  salt  solution, 
is  considered  to  justify  the  correction.  For  instance,  Table  XI  shows 
that,  within  the  error  of  observation,  sodium  and  potassium  chlorides 
satisfy  the  equation  X^n^/a  where  X  is  the  contraction  on  100,000 
cubic  centimetres,  n  the  number  of  gram  equivalents  in  the  same,  and 
a,  b,  are  constants.  The  concordance  with  this  equation  is  not  affected 
by  the  apparatus  used,  or  the  side  of  it  which  contains  the  solution. 

Errors  in  Titration, — ^In  the  greater  part  of  the  solutions  examined, 
an  error  of  0*1  c.c.  in  the  titration  would  correspond  to  a  change  in 
the  contraction  which  could  not  be  measured. 

Error  of  Temperature, — ^The  most  troublesome  error  is  that  due  to 
measurement  of  temperature,  and,  unlike  all  the  other  sources  of 
error,  its  effect  is  not  proportional  to  the  magnitude  of  contraction. 
The  greatest  percentage  effects  are,  therefore,  produced  in  the  dilute 


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DILUTION   OF  AQUEOUS  SOLUTIONS.  267 

solutions.  In  spite  of  the  very  thorough  stirring  and  continued 
readings  of  the  apparatus  and  thermometer,  the  uncertainty  in  the 
temperature  of  the  apparatus  (not  the  thermometer)  may  have  reached 
0*01^.  Two  opposite  errors  of  this  magnitude  would  affect  the 
apparent  oontraction  hy  ahout  0-2  unit. 

Concordance  of  RcsvUm, — ^The  general  concordance  of  the  final  results 
leads  to  the  conclusion  that  the  error  in  the  weakest  solutions  is 
about  0*2  unit,  and  that  it  may  grow  to  0*5  in  the  strongest.*  Of 
ooorse  this  does  not  disprove  the  existence  of  a  systematic  error,  but 
such  an  error,  if  it  exists,  would  certainly  tend  to  be  exposed  by  using 
different  patterns  of  apparatus.  The  five  instruments  employed  varied 
widely  in  dimensions,  yet  no  evidence  of  a  characteristic  error  was 
found  in  them. 

In  the  weak  solutions  of  sodium  chloride,  there  is  good  concordance 
between  the  contractions  measured  directly  and  those  calculated  from 
Kohlrausch  and  Hallwachs'  density  tables.  In  the  stronger,  the  con- 
cordance is  not  so  good,  but  then  in  such  solutions  Kohlrausch  and 
Hallwachs  have  availed  themselves  of  earlier  numbers  by  Gerlach, 
which  are  only  stated  to  five  places  of  decimals.  A  comparison  is 
made  in  Table  YIIL 

Table  VTIL 

Compariacn  of  contractions  (X)  in  cubic  centimetres  per  100,000 
observed  by  the  author  with  those  calculated  from  Kohlrausch  and 
UaUvoaeht^  tables :  nisihe  number  of  gram  equivalents  per  100,000 
cubic  centimetres  qf  diluted  solution. 


n 

10  2*0  X  (Kohlrausch  and 

Hallwachs) 2*8 

20  6-6  7*2 


80  180  147 

40  21*1  24-4 

60  30*9  82*5 


VII.  Tlie  Experiments. 

Material  Employed. — ^The  substances  chosen  for  the  measurement  of 
contraction  are  representatives  of  the  more  important  classes  of  com- 
pounds. Neutral  compounds,  which  are  supposed  to  remain  un  dis- 
sociated in  solution,  are  represented  by  cane  sugar  and  carbamide; 

*  In  the  case  of  strong  solutions  of  cane  sugar  and  potassinm  ferrocyanide,  the  error 
is  somewhat  greater,  but  in  these  solutions  the  method  of  finding  the  concentration 
was  not  so  accurate  as  for  the  chlorides ;  and,  secondly,  the  contraction  was  increas- 
ing Tery  rapidly  with  the  concentration,  so  that  errors  in  finding  the  concentration 
weze  of  greater  importance  than  usuaL 


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268 


WADE  ;  THE  CHANGES  OF  VOLUME  DUE  TO 


salts  dissociating  into  two  paris,  by  chlorides  of  sodium,  lithiom,  and 
potassium  3  salts  dissociating  into  three,  by  chlorides  of  calcium  and 
strontium;  salts  dissociating  into  more  than  three,  by  potassium  ferro- 
cyanide.  Mineral  acids  are  represented  by  hydrochloric  acid,  and 
organic  acids  by  oxalic  acid.  The  purest  commercial  samples  were 
used,  and  as  far  as  possible  they  were  recrystallised  and  their  purity 
confirmed  by  analysis.  Sodium  chloride  was  recrystallised  from  strong 
hydrochloric  acid,  and  the  acid  carefully  removed,  the  salt  washed  with 
a  little  water,  and  finally  ignited.  The  sample,  on  analysis,  gave 
01  =  60*4  per  cent. ;  Calculated,  60*6  per  cent.  Potassium  chloride  on 
analysis  gave  01  =  47*8  per  cent.;  Calculated  47  "6  per  cent.  A  best 
commercial  sample  of  lithium  chloride  was  dissolved  in  water  and 
filtered  from  the  very  slight  trace  of  insoluble  matter.  The  ratio  of 
lithium  to  chlorine  was  then  determined.  Found  1  :  5*3 ;  Calculated 
1  :  504. 

The  observations  marked*  in  Table  XI  were  obtained  with  a  com- 
mercially pure  calcium  chloride,  the  remainder  with  a  solution  on  which 
special  pains  had  been  taken  ;  the  latter  was  made  by  acting  on  per- 
fectly limpid  crystals  of  Iceland  spar  with  very  pure  hydrochloric  acid 
made  from  redistilled  sulphuric  acid,  and  the  sodium  chloride  already 
mentioned.  The  spar  was  in  excess,  and  the  solution  was  filtered 
from  it. 

FrdimvMvry  HxperimerUa. — Several  series  of  preliminary  experiments 
were  made  on  sodium  and  potassium  chlorides  while  learning  the 
manipulation ;  the  earlier  ones  were  faulty  and  discordant,  but  the 
later  ones  may  be  worth  placing  on  record,  although  they  did  not 
attain  the  accuracy  of  the  final  series. 


Table  IX. 
Preliminary  ohaervcUians  on  KOI,  NaCl. 


KCL 

NaCl. 

Explanation. 

n. 

X, 

w. 

X 

n. 

X 

15  0 

6-0 

84-5 

180 

12-6 

4 

n= number  of  gram  equi- 

160 

60 

36-6 

21-0 

19-0 

5 

Talents  per  100,000  cc„ 

19-0 

7-0 

45-6 

27-0 

22*0 

8 

and  Xs=  contraction  in 

24-4 

11-0 

47-0 

81-0 

22-0 

8 

c.c.  per  100,000  of  the 

24*5 

10  0 

47-7 

29-0 

26-0 

10 

eolation  due  to  60  per 

29-0 

14  0 

48-4 

82-0 

49-0 

29 

cent,  dilution. 

80-0 

16-0 

60-0 

88  0 

60'6 

88 

81-0 

16-0 

60-1 

84-0 

61-6 

88 

81-5 

140 

61-4 

85-0 

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DILUTION   OF   AQUEOUS   SOLUTIONS. 


269 


The  faalts  known  to  be  still  present  in  these  observations  were 

(1)  imperfect  stirring,  with  consequent  uncertainty  of  temperature, 

(2)  insufficient  attention  to  the  '  levelling '  (see  section  III.).  The 
first  error  was  removed  by  the  introduction  of  Mr.  Thomas'  stirring 
gear  after  the  series  on  sodium  chloride  was  completed  and  that  on 
potassium  chloride  was  about  half  complete.  The  second  was  not 
properly  understood  until  the  close  of  the  two  preliminary  series,  and 
from  that  time  irregularities  disappeared. 

27ie  Final  ExperimentaZ  Results, — Tables  X  and  XI  give  the 
results  obtained  when  everything  was  in  working  order.  X  repre- 
sents as  before  the  contraction  in  cubic  centimetres  per  100,000  and 
n  the  number  of  gram  equivalents  in  the  same ;  X  (calc.)  are  the 
numbers  deduced  from  the  equation ;  X  (calc.)  =  w*/a,  which  was  found 
to  answer  well  in  most  cases. 


Tablb  X. 
KCl.     a  =  191;  6  =  1-64. 


n. 

X  (calc.) 

X 

T. 

n. 

Z(calc.) 

X. 

T. 

9-60 

218 

2-8 

4R 

32*80 

16-12 

16-8 

8R 

12-66 

8-38 

8-6 

8  L 

83-46 

16-64 

16-4 

8R 

18  16 

8-60 

8-8 

8  L 

84-40 

17-42 

17-1 

4R 

18-66 

6-41 

6-1 

8  L 

37-20 

19-81 

19-7 

3R 

21-3 

7-70 

7-7 

Al 

48-20 

.30-29 

30-6 

3  L 

24-2 

9-79 

9-8 

3  L 

j     60-0 

82-18 

31-7 

4  L 

24-2 

979 

9-9 

8  L 

1     62-45 

84-6 

84-3 

A  1 

26-26 

11-18 

11-2 

8  R 

61-0 

33-3 

38  0 

A  1 

27-8 

11-8 

11-8 

4  L 

49-2 

31-3 

31-8 

3  L 

80-60 

14-2 

14-4 

Al 

36-6 

18-3 

18-6 

8R 

80-86 

14-68 

14-2 

8  L 

NaCl.     0  =  250;  h  = 

1-70. 

n. 

Z(calc.) 

X, 

r. 

3R 

n. 

Z(calc.) 

X 

r. 

9-60 

1-87 

1-6 

49-80 

30-20 

30-4 

4  L 

10-70 

2-25 

2-3 

8  L 

49-40 

80-29 

30-0 

4  L 

16*86 

4-87 

4-9 

3  L 

49-60 

80-41 

29-9 

4  L 

21-46 

7-11 

7-1 

8  L 

60-00 

30-98 

31-6 

3R 

22-60 

8-02 

8-0 

3  L 

60-62 

81-67 

81-4 

8R 

89-85 

2104 

21-4 

3  L 

60-90 

31-86 

81-6 

4R 

49-10 

29*96 

29-7 

4R 

62-95 

34-18 

84-2 

8  L 

Numerous  observations  were  made  on  these  salts  in  order  to  test 
experimental  error  and  the  influence  of  the  apparatus  used.  The 
names  of  the  appai*atu8  appear  under  T,  and  letters  R,  L,  indicate 
whether  solution   was  in   right   or   left   bulb.     For   the   remaining 

VOL.  LXXV.  T 

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270 


WADE:   THE  CHANGES   OF  VOLUME   DUE  TO 


Bubstances,  a  smaller  number  of  observations  have  been  thought 
sufficient,  and  the  results  are  contained  in  Table  XI,  using  the  same 
notation  as  before. 

Table  XI. 


SrClg. 
a=12-59;  6=1-54. 

CaOla. 
a=18-275;  6=1-52. 

n. 

JC  (calc.) 

X, 

w. 

X  (calc) 

X 

12-54 
12-92 
18-16 
19-52 
29-76 
32-57 
46-95 
47-02 

8-90 

4-09 

6-90 

7-71 

14-76 

16-96 

29-80 

29-86 

40    . 

4-4 

6-5 

8-3 
14-8 
15-8 
80-2 
30-0 

9-90 
10-40 
12-55 
1501 
24-0 
30-85 
49-18 

2-50 
2-65 
3-52 
4-62 
9-44 
13-49 
28-02 

2-8. 
2-4* 
3-8 
4-8» 
9-0 
13 -4» 
28-1 

CaM  sugar. 

1 
1 

LiOL 

• 

a= 

=  57-15;  6=2-00. 

!                  a= 

19-28;  6=1-528. 

n. 

X  (calc.) 

X 

1               71. 

X  (calc.) 

X 

13-9 

3-38 

8-5 

13-85 

2-87 

2-7 

24-3 

10-33 

10-2 

20-66 

5-29 

5-4 

80-01 

15-76 

15-8 

85-86 

12-80 

11-0 

48-99 

42-00 

41-6 

86-80 

12-80 

13  0 

49-3 

42-54 

43-4 

1        87-00 

12-91 

13-2 

49-9 

43-57 

44-5 

45-96 

18-00 

17-6 

50-9 

45-32 

44-7 

• 
a= 

HCl. 
=  29-45;  6  =  1-49. 

C,HA. 

n. 

X  (calc.) 

X 

n. 

X. 

16-52 

2-21 

2-0 

15-70 

7-2 

24-72 

4-04 

3-8 

20-48 

9-1 

26-51 

4-48 

4-7 

80-03 

13-2 

3000 

5-39 

6-1 

84-44 

15-8 

48-50 

1103 

11-4 

48-40 

19-6 

61-00 

11-88 

11-4 

48-6 
1        55-99 
60-00 

19-2 
22-4 
23-4 

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DILUTION   OP   AQUEOUS   SOLUTIONS. 


271 


Table  XL — carUintLed, 


K,FeC,N«.                           1 

CO(NH,V 

n. 

X. 

Tt, 

X, 

8-70 

10-5 

60 

3-4 

6-95 

19-9 

50 

8-6 

6-99 

19-9 

26 

0-4 

7-82 

25-0 

25 

0-6 

10-9 

42-1 

14-50 

667 

1511 

69-8 

VIII.  Discfisaion  of  EestUts, 

Methods  of  Formulating  the  Resulta, — Several  methods  of  represent- 
ing the  results  were  attempted,  and  at  first  it  seemed  probable  that 
an  equation  of  the  form  X=An  +  Bn^  would  be  satisfactory,  but  as 
greater  accuracy  was  attained  it  became  clear  that  the  deviation  from 
this  equation  was  systematic  and  greater  than  the  error  of  obser- 
vation. Finally,  the  equation  X^n^ja  was  used,  and  in  most  cases 
gives  values  of  X  agreeing  well  with  observation.  In  the  case  of 
oxalic  acid  and  potassium  ferrocyanide,  this  equation  does  not,  how. 
ever,  seem  to  express  the  results.  The  comparison  of  the  values  of 
X  calculated  from  the  equation  with  those  actually  observed  is  made 
in  Tables  X  and  XI,  and  Fig.  3  (p.  272)  shows  curves  drawn  from  the 
equation.  The  logarithms  are  plotted,  not  the  actual  values  of  X  and  n. 

Relation  of  Contraction  to  Equivalent  Weight, — If  the  contractions 
due  to  diluting  the  various  substances  examined  are  written  down  in 
order  of  magnitude,  they  will  be  found  to  stand  in  the  same  order  as 
the  equivalent  weights  of  the  substances.  This  is  shown  in  Tables 
XII  and  XIII,  which  contain  the  results  for  electrolytes  and  non- 
electrolytes  respectively. 

Table  XIL 


Name  and  equivalent  weight  of 

Contraction  due  to  diluting  from 
normal  to  half-normal. 

dissolved  substance. 

HCl 

86-5 

11-5 

LiCl 

42-6 

20-5 

iC»HaO, 

45 

20-8 

iCaCl, 

55-5 

28-8 

NaCl 

58-5 

80-9 

KCl 

74-5 

32-2 

^rCl, 

89-5 

82-8 

4K4FeC«N, 

92-0 

510 

Digitized  by 


Gobble 


272       WADE:  THE  CHANGES  OF  VOLUME  DUE  TO 

Fio.  8. 


y. 


'(^ 


W- 


r 


5< 


k- 


\^A/^ 


Explanation. 

n=Ti'*  of  gram  eq^iivaUnts  in 
100,000  e.c,  of  solution  aft&r 
diltUion. 

X= contraction  in  e.c.  per 
100,000  e.c.  of  solution,  due  to 
mixing  equal  volumes  of  water 
and  solution. 


Table  XIII. 


CO(NH,), 60 

Ci,H„On 342 


8-6 
48*8 


The  curve,  Fig.  4,  shows  the  contraction  as  a  function  of  the  equiva- 
lent weight ;  electrolytes  alone  are  considered,  and  with  the  exceptioi) 


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DILtJTlOK   OF  AQUEOUS  SOLUTIOKS. 


273 


of  potassium  ferrocjanide  the  relation  seems  well  marked.  Non- 
electrolytes  evidently  contract  very  much  less,  other  things  being 
equal,  than  electrolytes,  but  there  are  not  sufficient  data  as  yet  to  con- 
struct a  curve. 


Fio. 

4. 

.  '^ 

^ - 

— c 

c 

xt% 

oO 

y 

Y^ 

or 

§ 

cA 

/ 

ZO 

•5 

1 

y 

/ 

a 

/ 

10 

1/ 

f 

/ 

Equiwahnt   Weight. 

; — r-*i      1 

30 


40 


SO 


60 


70 


80 


90 


CorUniction  Regarded  ae  Change  in  the  Volume  qf  Dissolved  Substance, 

Perhaps  the  most  interesting  way  to  look  at  the  contractions  is 
to  consider  them  as  changes  in  the  apparent  volume  of  the  dissolved 
substance.  For  if  the  observed  contraction  is  divided  by  n,  the 
quotient  is  the  change  in  the  apparent  volume  of  1  gram  equivalent 
of  dissolved  substance  in  undergoing  50  per  cent,  dilution.  This  is 
expressed  in  the  equation 

^2n  -  ^  =  ^h  =  n^-'^/a, 

where  ^,  ^  are  the  apparent  volumes  of  1  gram  equivalent  of  dis- 
solved substance  before  and  after  the  50  per  cent,  dilution,  n  the 
number  of  gram  equivalents  per  100,000  after  dilution  (and,  therefore, 
2n  the  number  before).     The  solution  of  this  equation  is 

where  a,  b  are  known  from  the  tables  given  on  pp.  269,  270.  The 
remaining  constant  can  be  found  from  one  accurate  determination  of 
the  density,  and  where  such   a   determination  has  been  placed  on 

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274 


WABE:  THE  CHANGES  OF  VOLUME  DUE  TO 


record   it   is   possible   to  make    complete    tables    of   ^  at  various 
strengths. 

Table  XIV  gives  such  values  of  ^. 


Table  XIV. 
Substance  NaCl.    Temperature  18° 


I. 

n. 

^•CODSt. 

in. 

IV. 

n. 

Const,  assumed. 

*. 

10 

0-8211 

16-361 

16-68(2) 

20 

0-52U 

16-88(2) 

30 

0-6944 

17-06(6) 

40 

0-8470 

17-20(8) 
17-86(1) 

60 

0-9902 

76 

1-8163 

17-67(6) 

100 

1-6090 

17-97(0)  ♦ 

This  number  is  based  on  an  observation  by  Gerlach. 


SvhaUmce  SrClj.     Temperature  18-0°. 


10 

0-6066 

10-862 

11-46(9) 

20 

0-8819 

11-78(4) 

80 

1-0976 

11-96(0) 

40 

1-2820 

12  18(4) 

60 

1-4449 

12-29(7) 

76 

1-7983 

12-65(0) 

100 

2-1029 

12-96(6) 

65-8 

1-6776 

12-68  • 

This  number  is  based  on  an  observation  by  Eohlrausch. 


Substance  CaClj.     Temperature  18°. 


10 

0-6749 

10-149 

10-72(4) 

20 

0-8244 

10-97(8) 

80 

1-0179 

1116(7) 

40 

1-1823 

11-83(1) 

50 

1-3276 

11-47(7) 

76 

1-6890 

11-78(8) 

100 

1-9038 

12-06(8) 

98-8 

11-99(0)* 

This  number  is  based  on  an  observation  by  Eohlrausch. 

Digitized  by  VjOOQIC 


DILUTION   OF  AQUEOUS   SOLUTIONS. 


275' 


Table  XIV. — continued. 
Substance  HCl.     Temperatttre  IS"". 


I. 

IL 

III. 

IV. 

n. 

^-CODBt 

Const,  assumed. 

♦. 

10 
20 
80 
40 
60 
76 
100 

0-2595 
0-3648 
0-4443 
0-6118 
0-5708 
0-6962 
0-8013 

17-819 

18  07(9) 
18-18(8) 
18-26(8) 
18-88(1) 
18-89(0) 
]8-61(6) 
18-62(0)* 

*  Based  on  an  observation  by  Eohlratiach. 
Substcmce  O^jPSjs^ii*     Temperature  18° 


10 

0176 

209-750 

209*92(6) 

20 

0-360 

21010(0) 

SO 

0-526 

210-27(5) 

40 

0-700 

210-45(0) 

50 

0-876 

210-62(5) 

76 

1-812 

21106(2) 

100 

1-760 

211-60(0)* 

*  Based  on  an  observation  by  Gerlach. 
Svletance  KCl.     Temperature  20°. 


10 

0-4094 

26-685 

27-09(4) 

20 

0-6380 

27-82(3) 

30 

0-8272 

27-51(2) 

40 

0-9941 

27-67(9) 

60 

1-1468 

27-83(2) 

76 

1-4860 

28-17(1) 

100 

l-7»70 

28-47(2) 

107-7 

1-8746 

28-56(0)* 

*  Based  on  an  observation  by  Nicol. 


Substance  LiCl. 

Temperature  18° 

10 

0-8956 

18-408 

18-80(4) 

20 

0-6662 

18-97(4) 

80 

0-7078 

19-11(6) 

40 

0-8246 

19-23(3) 

60 

0-9280 

19-82(8) 

76 

1-1608 

19-66(9) 

100 

1-8400 

19-74(8) 

120-9 

1-4821 

19-89(0)* 

Based  on  an  observation  by  Kohlransch. 


Googk 


276  WADE:   THE   CHANGES   OF   VOLUME  DUE  TO 

The  curves  (Fig.  5)  exhibit  the  values  of  ^.  It  should  be  remembered 
that  the  author  is  only  directly  responsible  for  the  changes  in  ^^  and 
that  the  absolute  values  are  affected  by  errors,  if  any,  in  the 
'* constant  assumed"  which  is  dependent  on  the  accuracy  of  existing 
density  determinations. 

The  values  of  ^  are  given  partly  in  the  hope  that  they  will  prove  of 
practical  value  in  physico-chemical  work.  In  many  branches  of 
physical  chemistry,  solutions  are  prepared  by  dilution  of  stock 
solutions,  and  the  experimenter  wishes  to  know  the  concentration 
of  the  solution  obtained,  in,  say,  gram  molecules  per  100  grams 
of  water.  A  continuous  table  of  molecular  volumes  affords  the 
easiest  method  of.  arriving  at  the  result.  Partly,  again,  because 
the  values  of  X  only  tell  us  the  volume  change  on  50  per  cent, 
dilution,  whereas  the  tables  of  ^  gives  us  continuous  information  of 
the  change  of  volume  due  to  any  given  dilution.  In  the  diagram, 
Fig.  5,  ^  is  shown  as  a  function  of  n  for  various  substances.  As, 
however,  it  would  be  impossible  to  depict  the  various  curves  on  the 
same  page  without  greatly  diminishing  the  scale,  it  has  been  neces- 
sary to  subtract  a  constant  round  number  from  the  values  of  ^  before 
plotting.  These  numbers  are,  for  LiCl,  18;  NaCl,  16;  KCl,  27; 
HCl,  18  ;  CaClj,  10 ;  SrCla,  11 ;  Cane  sugar,  209. 

Conclusion, 

The  following  empirical  laws  have  been  arrived  at  by  the  experi- 
ments described. 

1.  JT  (as  defined  on  p.  268,  Table  IX)  is  in  almost  all  cases  given  by 
the  following  equation,  X«^n^/a,  and,  consequently,  ^  (as  defined,  p. 
273)  must  be  given  by 

ih  =  const.  H ^^.    ,,  ■ 

^  a(2''-il) 

2.  For  comparable  substances  and  concentrations,  X  increases  with 
the  equivalent  weight  of  the  substance  in  a  regular  way. 

It  is  hoped  that  these  empirical  rules,  together  with  the  tables  of 
contraction  and  of  molecular  volumes,  will  be  sufficient  excuse  for  the 
publication  of  this  paper.  It  should  be  added  that  the  apparatus 
described  is  applicable  without  modification  to  many  other  physico- 
chemical  problems,  such  as  change  of  volume  on  neutralisation,  change 
of  volume  on  mixing  two  different  liquids  (for  example,  alcohol  and 
water),  changes  of  volume  on  formation  of  double  salts  in  solution. 
The  author  hopes  to  proceed  with  the  study  of  volume  changes  on 
neutralisation  of  organic  acids  without  delay. 

The  writer's  best  thanks  are  due  to  Prof.  J.  J.  Thomson  for 
permission  to  work  in  the  Cavendish  Laboratory,  and  to  Mr.  Griffiths 
and  Mr.  Whetham  for  the  interest  taken  in  the  work  throughput.  _ 


DILUTION   OF   AQUEOUS  SOLUTIONS. 
Fig.  5. 


277 


.o 

I 

CO 


-2 
•  •I 
-0 
0-9 

-•8 
-•7 

-6 
-5 
-4 
-5 
-2 
^•1 


/   /      ^ 


10      20      30      40      SO      60      70      80      90     100 

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278  baqnall:  methanetrisulphonic  acid, 

XXIX. — Methanetrisulphonic  Acid. 

By  Ebnbst  Habold  Bagnall,  B.So. 

The  sulphonic  acids  of  methane,  the  Bimplest  hydrocarbon,  are  Bub- 
Btances  of  more  than  ordinary  intereet,  and,  although  the  mono-,  di-, 
and  tri-Bulphonic  acids,  CHj-HSOj,  CH3(HS03)2,  and  CH(HS08)s, 
have  long  been  known,  no  work  on  them  has  been  published  during 
the  last  fiye-and-twenty  or  thirty  years. 

Of  these,  methanetrisulphonic  acid,  0H(HS03)j,,  the  subject  of  this 
paper,  was  discovered  by  Theilkuhl  {Annalen,  1868,  147,  134),  and 
subsequently  examined  by  Eathke  {ihid.^  1873,  167,  219). 

In  attempting  to  prepare  the  various  sulphonic  acids  and  sulphones 
of  dichlorobenzidine  by  the  action  of  fuming  sulphuric  acid  on  dichloro- 
diacetylbenzidine,  a  substance  was  obtained  which,  on  analysis,  was 
found  to  be  methanetrisulphonic  acid ;  as  it  can  be  easily  prepared 
by  the  methods  described  in  this  paper,  I  have  carefully  examined  the 
acid,  and  also  studied  the  properties  of  its  various  salts. 

Preliminary  experiments  soon  showed  that  the  formation  of  methane- 
trisulphonic acid  was  really  due  to  the  presence  of  the  acetyl  groups 
in  dichlorodiacetylbenzidine,  as  diacetylbenzidine  under  similar  treat- 
ment gave  a  large  quantity  of  the  acid,  whereas  benzidine  sulphate 
gave  only  benzidinesulphone  and  the  various  sulphonic  acids  of 
benzidine  (Ber,^  21,  Rrf.^  873  ;  22,  2467).  Similarly,  acetyl-a-naphthyl- 
amine  gave  a  small  quantity  of  methanetrisulphonic  acid. 

As  this  reaction  appeared  to  be  a  general  one  for  the  acetyl  deri- 
vatives of  benzidine  and  naphthylamine,  it  was  anticipated  that  the 
acetyl  derivative  of  aniline  and  the  anilides  of  the  higher  fatty  acids 
would  yield  methanetrisulphonic  acid,  or  its  homologues,  as  one  of  the 
products,  and  this  was  found  to  be  so  in  the  case  of  acetanilide. 
Acetanilide,  when  heated  with  fuming  sulphuric  acid,  gives  a  remark- 
ably good  yield  of  methanetrisulphonic  acid,  along  with  anilinedi- 
sulphonic  acid,  NH,- CeH8(HS08)2  [1:2:4],  Other  anilides  were 
experimented  with,  but  the  results  were  not  satisfactory  ;  the  anilide 
of  propionic  acid  gave  a  very  small  quantity  of  methanetrisulphonic 
acid,  but  neither  ethanedisul phonic  acid  nor  sulphopropionic  acid  could 
be  detected  (compare  Buckton  and  Hofmann,  J,  Chnn,  Soc.^  1856,  0, 
p.  241). 

It  is  difficult  to  understand  the  general  nature  of  these  reactions. 
Much  sulphurous  anhydride  and  carbonic  anhydride  are  always  evolved, 
and  it  seems  probable  that  some  of  the  organic  substance  is  oxidised  to 
carbonic  anhydride,  and  some  converted  into  aromatic  sulphonic  acids, 

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BAONALL:  METHANETRISULPHONIC  ACID.  279 

the  acetjl  group  alone  reacting  with  the  fuming  sulphuric  acid  to 
form  methanetrisulphonic  acid.  Glacial  acetic  acid,  however,  when 
heated  with  fuming  sulphuric  acid,  gives  no  methanetrisulphonic  acid ; 
the  sulphur  trioxide  dissolves  in  the  acetic  acid  without  giving  off  gas, 
and  sulphaoetic  acid,  CH3(HS03)*COOH,  is  formed.  It  was  antici- 
pated that,  on  heating  acetamide  with  a  large  excess  of  fuming  sulphuric 
acid,  methanetrisulphonic  acid  would  also  be  produced,  but  this  is  not 
the  ease;  the  product  consists  entirely  of  methanedisulphonio  acid, 
GU^iBSO^^  which  was  first  isolated  by  Liebig  (Annalen,  1835,  13, 
35),  and  subsequently  prepared  and  examined  by  Wetherill  (ibid.,  1850, 
66,  122),  Strecker  {ibid,,  1856,  100,  199),  and  by  Buckton  and 
Hofmann  (J,  Chem.  Soc.y  1856,  0,  241),  and  Rathke  {Annalen,  1873, 
161,  152). 

EXPBBIMBKTAL. 

Preparation  of  MethaaieiirisulpTionic  Acid, 

Action  of  Fwning  Sul/phuric  Acid  on  Dichlorodiaeett/lbenzidine. — 
As  stated  in  the  introduction,  it  was  from  this  substance  I  first 
obtained  methanetrisulphonic  acid.  Dry  powdered  dichlorodiacetyl- 
benzidine  (16*85  grams)  was  heated  on  a  water-bath  at  100^  with 
fuming  sulphuric  acid  (100  grams,  containing  70  per  cent,  free  SO3), 
mixed  with  pure  sulphuric  acid  (100  grams)  until  the  whole  dissolved.* 
The  mixture  was  then  heated  for  3  hours  on  a  sand-bath  at  a  tempera- 
ture of  150^,  with  constant  stirring,  and  left  overnight.  It  was  then 
poured  on  to  ice,  filtered  to  remove  a  dirty  green  precipitate  which 
probably  contains  the  sulphones  and  sulphonio  acids  of  dichlorobenz- 
idine,  and  the  dark  brown  filtrate  neutralised  with  milk  of  lime,  heated 
to  boiling,  and  rapidly  filtered  from  the  precipitated  calcium  sulphate. 
To  the  clear  filtrate,  evaporated  to  a  small  bulk,  sodium  carbonate 
solution  was  added  in  quantity  just  sufficient  to  precipitate  all  the 
calcium  as  carbonate.  This  was  filtered  off,  and  the  filtrate  concentrated 
and  allowed  to  cool  slowly,  when  it  deposited  yellow  crystals ;  these 
were  collected,  dissolved  in  a  small  quantity  of  water,  and  glacial 
acetic  acid  added ;  the  white,  crystalline  precipitate  of  the  sodium  salt 
of  methanetrisulphonic  acid,  Cn(!N'aSOg)g  +  SHjO,  thus  obtained,  was 
analysed. 

*  Great  care  is  required  in  the  mixing  of  fuming  sulphuric  acid  with  concentrated 
sulphuric  acid ;  to  prevent  accident,  the  concentrated  sulphuric  acid  should  be  poured 
into  the  fuming  acid,  not  vice  versd. 

It  is  better  to  carry  out  these  snlphonations  in  a  porcelain  beaker,  the  mouth  of 
which  IB  covered  with  a  close-6tting  clock-glass.  A  hole  is  bored  through  the 
centre  of  the  clock-glass,  so  as  to  admit  a  glass  stirring  rod  which  is  connected 
with  a  water-motor.  With  this  arrangement,  very  little  sulphuric  anhydride  escapes 
into  the  air. 


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280  BAGNALL:  M ETHAN ETRISULPHONIC  ACID. 

0-1926,  dried  at  160°, lost  00276  H^O,    Hfi  =  14-33. 

0-2902  (anhydrous  salt)  gave  0-0363  COg  and  0-1200  HgO.  0  =  3*31 ; 

H  =  0-45. 
0-1799  (anhydrous  salt)  gave  01188  'Nd^SO^.    Na  =  21-39. 
0-0785  „  „        „     0-1720  BaSO^.    8  =  30-08. 

CH(NaS0s)8require8C  =  3-72;  H  =  0-31 ;  Na  -  21-42,;  S  «  29-81  percent. 
CH(NaS03)8  +  3H2O  requires  HgO- 14-36. 

This  salt  crystallises  in  six-sided  plates,  with  3H2O,  easily  soluble 
in  water,  and  is  not,  therefore,  as  suitable  as  the  potassium  salt  for 
isolating  methanetrisulphonic  acid  from  an  aqueous  solution.  On 
heating  the  anhydrous  sodium  salt  in  a  tube,  sulphur  sublimes  and 
sulphurous  anhydride  is  evolved,  together  with  a  little  hydrogen 
sulphide  and  carbon  bisulphide ;  the  residue  consists  almost  entirely  of 
sodium  sulphate.  It  is  remarkable  that  when  glacial  acetic  acid  is 
added  to  an  aqueous  solution  of  sodium  methanetrisulphonate,  the  salt 
is  precipitated  almost  completely  in  crystals. 

Action  of  Fuming  StUphuric  Acid  on  Diacetylbenzidine, — In  this 
experiment,  100  grams  of  fuming  sulphuric  acid  containing  70  per 
cent,  free  SOg,  50  grams  of  concentrated  sulphuric  acid,  and  20  grams 
of  dry,  powdered  diacetylbenzidine  were  used,  the  operation  being 
carried  out  exactly  as  in  the  first  case,  with  the  exception  that  the 
calcium  salt  was  decomposed  with  potassium  carbonate  ;  the  potassium 
salt  thus  obtained  is  much  less  soluble  in  water  than  the  sodium  salt, 
and,  therefore,  more  suitable  for  the  isolation  of  the  acid.  The  yield 
of  potassium  methanetrisulphonate  obtained  is  very  good,  the  above 
quantities  yielding  about  35  grams  of  the  pure  salt. 

Action  of  Fuming  Sulphuric  Acid  on  Acetyl-a-napWi,ylamine, — ^One 
hundred  grams  of  dry,  powdered  acetyl-a-naphthylamine,  prepared 
in  the  usual  way,  was  heated  with  100  grams  of  fuming  sulphuric 
acid  (70  per  cent^SOg)  and  50  grams  of  concentrated  sulphuric  acid, 
as  in  the  other  cases.  The  yield  of  methanetrisulphonic  acid  pro- 
duced in  this  way  is  but  poor,  considerable  quantities  of  ammonium 
sulphate  being  formed  during  the  reaction. 

Action  of  Fuming  Sulphuric  Add  an  Acetanilidc, — As  this  method 
gives  the  best  yield  of  methanetrisulphonic  acid,  it  is  described  in 
detail.  Five  grams  of  dry,  powdered  acetanilide  were  slowly  added  to 
a  mixture  of  30  grams  of  fuming  sulphuric  acid  (70  per  cent,  free  SOg) 
and  15  grams  of  pure  concentrated  sulphuric  acid,  the  mixture  being 
constantly  stirred  and  heated  at  130°  for  three  hours.  The  amber- 
coloured,  viscous  product,  when  cold,  was  poured  into  water,  boil  ed, 
and  neutralised  with  milk  of  lime ;  not  a  trace  of  aniline  was  li  be- 
rated. The  liquid  was  filtered  hot,  and  sufficient  potassium  carbonate 
solution  added  to  the  filtrate  to  convert  the  soluble  calcium  salts 


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JBAGNALL:  M£THANETRISULPHONIC  ACID.  281 

into  the  potassium  salts.  The  filtrate  from  the  calcium  carbonate, 
when  concentrated  and  left  to  cool,  deposited  beautiful,  colourless 
prisms  of  almost  pure  potassium  methanetrisulphonate.  These  were 
collected,  drained  on  a  porous  plate,  and  recrystallised  from  boiling 
water.     On  analysis,  they  gave  the  following  results. 

1  -7380,  dried  at  210°,  lost  0-0803  HgO.     HgO  =  4-62. 

1-2043  (anhydrous  salt)  gave  0-1630  COj  and  0-0346  HgO.   C  =  3-46  ; 

H  =  0-31. 
0-5106  (anhydrous  salt)  gave  0*3600  KgSO^.     K  =  31-61. 
0-6259  „  „        „     1-1972  BaSO^.     8  =  26-26. 

CH(KS08)3  requires  C  =  3-24  ;  H  =  0-27 ;  K  =  31-62 ;  S  =  25  94. 
CH(KS03)3  +  H30  requires  HjO  =  4-64. 

This  potassium  salt  loses  its  water  of  crystallisation  at  210°,  and 
when  heated  in  a  tube  behaves  like  the  sodium  salt.  It  is  insoluble  in 
absolute  alcohol,  ether,  and  glacial  acetic  acid,  and  is  only  sparingly 
soluble  in  cold  water,  1  part  requiring  89  parts  at  18°  for  solution  ;  it 
dissolves  readily  in  hot  water,  from  which  it  is  again  deposited,  on 
slowly  cooling,  in  beautiful,  colourless  prisms  often  over  an  inch  in 
length.  Phosphorus  pentachloride  has  no  action  on  the  anhydrous 
salt.  As  in  the  case  of  the  sodium  salt,  glacial  acetic  acid  precipitates 
the  potassium  salt  and  all  the  other  salts  of  methanetrisulphonic  acid, 
unchanged  from  their  aqueous  solutions. 

To  trace  the  part  the  aniline  took  in  the  action  of  fuming  sulphuric 
acid  on  acetanilide,  the  mother  liquor  from  the  first  crop  of  crystals 
of  potassium  methanetrisulphonate  was  further  concentrated  and 
placed  on  one  side  to  cool,  when  a  second  crop  of  crystals  of  the  tri- 
sulphonate  was  obtained ;  these  were  filtered  ofiE  and  the  filtrate 
fractionally  precipitated  by  glacial  acetic  acid.  The  precipitate,  first 
formed  on  adding  glacial  acetic  acid,  was  rejected  as  retaining  gene- 
rally traces  of  potassium  methanetrisulphonate.  The  further  addition 
of  glacial  acetic  acid  to  the  filtrate  produced  a  white,  silky  precipitate 
of  the  hydrogen  potassium  salt  of  anilinedisulphonic  acid, 

NHj-CeH,(KS03)-HS08  [1:2: 4], 
first  prepared  by  Buckton  and  Hofmann  (loe.  cit.)  by  the  action  of 
fuming  sulphuric  acid  on  aniline.   The  anhydrous  salt  gave  the  follow- 
ing results  on  analysis. 

0-3318  gave  0-3042  CO^  and  00662  H^O.     C  =  25-00;  H«2-20. 
01807     „    0-0541X2804.     K=  13-43. 
0-2815     „    0-4410  Ba804.    8  =  2151. 

0-3151     „     13  c.c.  nitrogen  at  775-2  mm.  and  20°.     N  =  4-92. 
NH5-CeH3(K803)-HS03    requires    0  =  24-74;    H  =  2-06;    8  =  21-99; 
K  =  13-40;  N^4-81. 

1?o  fiirther  identify  this  substance,  it  was  dissolved  in  water  and 


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282  BAQNALL:  METHANBTRISULPHONIC  ACID. 

treated  with  bromine  water  ;  the  yellow  precipitate  produced  sublimed 
in  beautiful,  colourless  needles  which  melted  at  137^,  and  gave,  on 
analysis,  numbers  corresponding  with  the  formula  of  )3-tribromaniline 
GgHgBrg'NHs  [1:2:4: 5].  The  production  of  the  acid  potassium 
salt  of  anilinedisulphonic  acid  in  the  above  reaction  is  due  to  the 
fact  that  glacial  acetic  acid,  when  added  to  an  aqueous  solution  of  the 
neutral  potassium  salt  of  anilinedisulphonic  acid,  throws  down  the 
acid  potassium  salt,  which  is  much  less  soluble  in  water  than  the 
neutral  salt. 

Action  of  Fuming  Sulphwrio  Acid  on  FropanUide, — ^Thirty  grams  of 
pure,  powdered  propanilide  were  added  in  small  quantities  to  a  mixture 
of  110  grams  of  fuming  sulphuric  acid  (70  per  cent.  SO3)  and  50  grams 
of  concentrated  sulphuric  acid,  and  the  whole  heated  at  110°  for  two 
hours  ;  on  cooling,  the  product  was  poured  into  water,  and,  curiously 
enough,  ethylic  alcohol  was  given  off.  The  solution  was  treated  as  in 
the  other  cases,  first  with  milk  of  lime,  and  subsequently  with  a  solution 
of  potassium  carbonate ;  in  this  way,  a  substance  was  obtained  which, 
after  recrystallisation  from  dilute  acetic  acid,  gave  numbers,  on  analysis, 
showing  it  to  be  the  hydrogen  potassium  salt  of  anilinedisulphonic 
acid,  N'Hj-OeH3(KS03)-HS03  [1:2: 4].  By  this  method,  anilinedisul- 
phonic acid  alone  is  isolated;  to  obtain  what  little  methanetrisulphonic 
acid  is  formed,  the  product  was  poured  into  water,  neutralised  with 
calcium  carbonate,  filtered,  and  the  filtrate  treated  with  excess  of  a 
solution  of  ammonium  carbonate ;  it  was  then  again  filtered,  boiled  with 
barium  carbonate,  and  filtered  while  hot.  On  cooling,  a  small  quantity 
of  a  crystalline  barium  salt  separated  which  showed  all  the  characteristic 
properties  of  barium  methanetrisulphonate.  The  salt,  dried  at  180°, 
was  analysed. 

01117  gave  0-0844  BaSO^.     Ba  =  4443. 

Ba3[CH(S03)3]2  requires  Ba  =  44-82  per  cent. 

What  part  the  propionic  radicle  takes  in  this  reaction  it  is  not  easy 
to  say  3  certainly  a  large  quantity  of  the  acid  escapes  during  the  re- 
action as  free  propionic  acid,  and  furthermore,  as  just  stateu,  ctbylic 
alcohol  is  also  produced,  which  must  have  come  from  this  source. 
Neither  ethanedisulphonic  acid  nor  sulphopropionio  acid  could  be  de- 
tected. 

MethanetristUphonic  Acid  and  its  Salts, 

Methanetrisulphonic  Acid. — In  preparing  this  acid,  the  pure  barium 
salt  was  suspended  in  warm  water  and  cautiously  decomposed  with  pure 
sulphuric  acid,  a  slight  excess  of  the  acid  being  used ;  after  heating 
on  the  water- bath  for  a  few  hours,  the  liquid  was  filtered  from  barium 
sulphate  and  evaporated  ;  the  syrupy  residue,  when  kept  for  2  or  3  days 


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BAQNALL:  METHANETRISULPHONIC  ACID.  283 

in  a  good  vacuum  over  sulphuric  acid,  deposited  beautiful,  colourless 
needles.  The  crystals,  after  draining  on  a  porous  plate  in  a  vacuum, 
gave  the  following  numbers  on  analysis,  very  accurate  results  being 
difficult  to  obtain  as  the  acid  is  exceedingly  hygroscopic. 

I.  0-6741  gave  00760  COg  and  0-2001  H^O.    C  =  303;  H  =  3-29. 
n.  0-5480     „    0-0557  COg    „     0-1636  HjjO.   C  =  2-77  ;  H  =  3-31. 

0-2720     „     0-6025  BaSO^  ;  S  =  3042. 
CH(HS03)g  requires  C  =  4-68  ;  H  =  1-56  ;  S  =  3760  per  cent. 
CH(HS03)8  +  4H2O  requires  C  =  3-66  j  H  =  3-65  ;  S  =  2926  per  cent. 

This  analysis  appears  to  show  that  the  acid  has  probably  the  formula 
OH(HS03)8  +  4H2O.  Unfortunately,  it  is  not  possible  to  estimate  the 
water  of  crystallisation  by  the  ordinary  method,  as  the  acid  decom- 
poses at  180^  before  all  its  water  of  crystallisation  has  been  given  o£E. 

Methanetrisulphonic  acid  melts  between  160°  and  153°,  and  dissolves 
very  easily  in  water  with  development  of  heat ;  it  is  very  deliques- 
cent^ has  a  pure  acid  taste,  and  turns  blue  litmus  red.  It  is  not 
changed,  and  no  sulphuric  acid  is  produced  by  boiling  it  with  nitric 
acid,  or  when  chlorine  gas  is  passed  through  an  aqueous  solution  of  the 
acid.  The  salts  of  methanetrisulphonic  acid  are  readily  obtained  by 
digesting  the  carbonates  of  the  various  metals  with  an  aqueous 
solution  of  the  acid.  The  barium  salt  is  precipitated  as  a  white, 
sparingly  soluble,  crystalline  precipitate  on  adding  barium  chloride 
to  an  aqueous  solution  of  the  acid.  The  other  salts  are  all  more  or 
less  soluble  in  water,  but  insoluble  in  alcohol,  and  in  glacial  acetic  acid. 
Phosphorus  pentachloride  has  no  action  on  it  in  the  cold,  but  on 
slightly  warming  decomposition  takes  place ;  it  was  not  possible,  how- 
ever, to  isolate  the  product  in  a  pure  state.  Methanetrisulphonic 
acid  immediately  unites  with  aniline  with  evolution  of  heat,  forming 
the  aniline  salt,  CH(HS03)3(CgH5-NH2V 

Silver  Methcmetrisidp/wnate,  CH(AgS03)3  +  HgO. — ^To  prepare  this 
salt,  freshly  prepared  silver  carbonate  was  added-  to  a  solution  of  the 
pure  acid  until  the  liquid  was  neutral,  and  the  filtrate  concentrated 
on  a  water-bath  and  allowed  to  cool,  when  slender  crystals  of  the 
sUver  salt  gradually  separated.  The  salt  crystallises  with  IH^O, 
which  it  loses  at  180°,  but  if  it  is  heated  above  180°,  it  darkens  and 
begins  to  decompose.  Silver  methanetrisulphonate  is  soluble  in  water, 
but  insoluble  in  absolute  alcohol. 

2-3612  lost  0-0748  Kfi  at  180°      H^O  =  3-18. 

1-2126  (anhydrous  salt)  gave  00915  COg  and  01950  HgO.    C  =  205  ; 
H  =  0-17. 

0-6477  (anhydrous  salt)  gave  0-3070  Ag.     Ag  =  6603. 

0-4298  „  „         „     0-5104  BaSO^.     S=  16-30. 

CH(S08Ag)8requiresC  =  207;  H  =  0-17;  Ag  =  6613;  S  =  16-63  percent. 
CH:( AgS03)8  +  HgO  requires  HgO  =  3  -02  per  cent. 

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284  BAGNALL:  METHANETRISULPHONIC  ACID. 

To  determine  the  sulphur  in  the  silver  salt,  Carius'  method  was 
first  tried,  but,  as  in  the  case  of  the  calcium  and  barium  salts,  the 
silver  salt  crystallised  out  of  the  nitric  acid  quite  unchanged  at  the 
end  of  the  process,  even  after  heating  at  a  temperature  of  210^;  this 
is  remarkable,  as  most  silver  salts  of  organic  acids  are  decomposed  by 
nitric  acid  under  these  conditions.  The  sulphur  is  easily  deter- 
mined, however,  by  fusing  the  salt  with  pure  potassium  nitrate  and 
carbonate. 

It  was  anticipated  that  the  ethylic  salt  of  methsuietrisulphonic  acid 
would  be  formed  by  heating  silver  methanetrisulphonate  with  ethylic 
iodide,  and  in  order  to  investigate  this  point,  4  grams  of  the  anhydrous 
silver  salt  were  mixed,  in  a  dry  flask,  with  6  grams  of  ethylic  iodide 
dissolved  in  absolutely  dry  ether,  and  the  mixture  heated  in  a  reflux 
apparatus  for  6  hours;  on  extracting  with  ether  and  removing  the 
ether  by  evaporation,  no  residue  was  left,  and  most  of  the  silver  salt 
was  recovered  unchanged. 

Barium  Methanetrisulphonate,  Ba3[CH(S03)8]2  +  OHgO.— When  a  sol- 
ution of  barium  chloride  is  added  to  a  solution  of  methanetrisulphonic 
acid  or  any  of  its  salts,  a  most  characteristic  behaviour  is  noticed,  and 
this  may  be  used  for  detecting  the  presence  of  methanetrisulphonic  acid ; 
on  mixing  the  two  solutions,  nothing  takes  place  for  a  few  moments, 
and  then,  suddenly,  a  crystalline  precipitate  of  the  barium  salt  separates. 
The  crystals  were  collected,  well  washed,  and  analysed. 

0-2189  (anhydrous  salt)  gave  0*1660  BaSO^.     Ba  =  44'68. 
0-5340  gave,  at  220°,  0*0810  H^O.     H20=  1516. 
Ba3[CH(S08)8j2  requires  Ba  =  44-82   and  Ba3[CH(S03)3]2  +  gH^O  re- 
quires H20=  1501  per  cent. 

Barium  methanetrisulphonat-e  dissolves  very  sparingly  in  boiling 
water,  and  crystallises  on  cooling  either  in  the  form  of  leaflets  or 
needles,  the  temperature  and  concentration  of  the  solution  evidently 
determining  the  crystalline  form.  Strong  nitric  acid  even  under 
pressure  does  not  decompose  the  barium  salt,  and  the  salt  crystallises 
unchanged  from  50  per  cent,  hydrochloric  acid. 

Calcium  Methamtrisulphanate,  Ca8[CH(803)3]2  +I2H2O.— This  salt 
crystallises  with  I2H2O  in  very  small  prisms  which  become  anhydrous 
at  180°.  It  is  very  soluble  in  water,  less  soluble  in  dilute  alcohol, 
and  insoluble  in  absolute  alcohol  or  glacial  acetic  acid,  and  remains 
unchanged  when  heated  under  pressure  with  nitric  acid  and  potassium 
dichromate. 

Capper  Methamtrisulphanate,  Cu3[CH(S08)3]2  +  I2H2O.— This  salt  is 
obtained  on  decomposing  barium  methanetrisulphonate,  suspended  in 
boiling  water,  with  the  requisite  quantity  of  a  solution  of  copper 
sulphate,  and  the  filtrate  from  the  barium  sulphate,  after  concen- 
tration on  a  water-bath,  is  left  overnight  over  sulphuric  acid  in  a 

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BAONALL:  METHANETRISULPHONIC  ACID. 


285 


Tacuam ;  prismatic  needles  of  the  copper  salt  gradually  separate,  and 
these,  after  draining  on  a  porous  plate,  were  analysed. 

1-2784  lost  0-3010  H^O  at  160^    HgO  =  23-51. 
0-2954    „  00780  CuO.     Ou  =  21-06. 
Cu3[OH(SOj)8]4+  I2H2O  requires  HjO  =  2371 ;  Cu=-  20-74  per  cent. 

Ammonium  Methaneirieulj^umate,  OH(NH^S03)3. — This  was  pre- 
pared by  neutralising  an  aqueous  solution  of  the  pure  acid  with 
ammonia,  and  exposing  the  solution  in  a  vacuum  over  sulphuric  acid, 
when  crystals  of  the  salt  separated. 

0-2995  gave  00493  NHg.     NH3  « 1646. 

0B:(NH4S03)g  requires  NHg- 1661  per  cent. 

Ammonium  methanetrisulphonate  appears  to  crystallise  in  stumpy 
prisms  or  plates,  probably  belonging  to  the  monosymmetric  system. 
This  research  was  carried  out  in  the  laboratories  of  the  Owens 
College,  Manchester,  at  the  suggestion  of  Professor  Perkin. 

Cbtstalloobaphioal. 

For  the  accompanying  measurements  of  silver  methanetrisulphonate, 
and  description  of  the  crystallographical  character  of  the  other  salts 
of  methanetrisulphonic  acid,  I  am  indebted  to  Mr.  W.  J.  Pope. 

Silver  Methaneirieulphonaie. — ^This  crystallises  in  small,  white,  opal- 
escent, iridiscent  plates  belonging  to  the  orthorhombic  system;  the 
crystals  are  somewhat  irregularly  developed,  and  the  faces  in  the  zone 
[100:010]  are  deeply  striated  with  lines  parallel  to  the  c  axis.  The 
extinction  in  a{100}  is  parallel  to  the  edge  ap,  and  the  acute  bisectrix 
emerges  normally  to  a(lOO) ;  the  optic  axial  plane  is  c(OOl),  the  optic 
axial  angle  is  large,and  thedouble  refractionis  negative  in  sign  and  weak. 

Crystalline  system. — Orthorhombic. 

a:h:e:^  2-9152:1:0*5422. 
Forms  present  a  {100},  b  {010},  p  {110},  g  {011}  and  g'  {012}. 

The  following  angular  measurements  were  obtained. 


ADgle. 

Number  of 
measurements. 

Limits. 

Observed. 

Calculated. 

ap  =100:110 
bp  =010:110 
pp  =110:110 
pp  =110:110 
bq    =010:011 
qq    =011:011 
qq"  =011:012 
/^  =  012:012 

17 
89 
24 
20 
82 
24 
11 
16 

18'22'--  19'  8' 
70  46  —  71  26 
14148—142  80 
87  81  —  88  11 
61  18  —  61  62 
66  81  —  67  28 
13    1—18  26 
80  14^  80  89 

18'49' 
71    4 
142    9 
87  46 
6182 
66  69 
18  14 
80  26 

18-66' 

142    8 
37  62 

66  56 
1818 
80  22 

VOL.   LXXV. 

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rQpgle 

286 


BROWN  AND   MILLAR:  MALTODEXTRIN  : 


Barium  SaU, — ^The  crystals  consist  of  minute^  rhomboidal  shaped 
plates,  the  acute  angle  being  76^  j  the  extinction  bisects  the  angles  of 
the  rhomb« 

Sodium  Salt* — ^The  crystals  consist  of  long,  six-sided  plates,  in  which 
the  extinction  is  parallel  to  one  pair  of  edges ;  the  large  face  is  per- 
pendicular  to  the  positive  bisectrix  of  a  large  optic  axial  angle. 

Potassium  SaU. — ^The  crystals  consist  of  large,  monosymmetrio  prisms, 
showing  the  forms  {100},  {001},  {110},  and  {111}.  The  optio  axial 
plane  is  perpendicular  to  the  plane  of  symmetry,  and  one  optic  axis 
emerges  nearly  normally  through  the  face  (110). 


XXX. — MaltodextHn:  its  Oxidation- Products  and 
Constitution, 

By  Horace  T.  Brown,  LL.D.,  F.R.S.,  and  J.  H.  Millar. 


Contents. 


I.  Introduction       .... 
II.  Preparation  of  Maltodextrin 
III.  Properties  of  Maltodextrin 
I Y.  Oxidation  of  Maltodextrin . 
Y.  Hydrolysis  of  Maltodextrinic  Acid  A . 
YI.  Maltrodextrinio  Acid  B 
YIL  Acid  Hydrolysis  of  Maltodextrinic  Acids  A  and  B 
YIIL  The  Final  Acid  obtained  by  the  Acid  Hydrolysis 
of  Maltodextrinic  Acids  A  and  B    . 
IX.  The  Constitution  of  the  Maltodextrinic  Acids  and 

Maltodextrin 

X.  Appendix,       The    Acid    Hydrolysis    of    Starch 
Derivatives 


FAGS 

286 
288 
292 
293 
296 
297 
298 

298 

300 

305 


I.  Introduction, 

In  a  paper  published  thirteen  years  ago  by  one  of  us  and  G.  H. 
Morris  (Trans.,  47,  1885,  527),  a  substance  was  described  under  the 
name  of  maltodextrin,*  which  had  been  isolated  from  a  mixture  of 

*  The  term  maltodeztrin  is  dae  in  the  first  instanoe  to  Herzfeld,  who,  as  far 
back  as  1879,  employed  it  to  describe  a  derivatiye  of  starch  which,  in  many  respects, 
although  not  in  all,  corresponded  with  the  subject  of  this  paper  (see  Hezzfeld, 
Inaug.Di83.ffalU,lS79;  also  ^er.,  1886, 18, 3469;  ifttef.,  1886, 19. 488).  More  recently, 
Armstrong  suggested  the  term  amyloln  as  being  generally  applicable  to  substances 
of  this  class.  Both  terms  are  oonyenient,  since  they  recall  the  fact  that  the  sub- 
stances in  question,  of  which  probably  a  series  exists,  may  be  regarded  as  combina- 
tions  of  amylin  or  dextrin  groups,  with  amylon  or  maltose  groups.    ^  t 


ITS  OXIDATION-PRODUCTS  AND  CONSTITUTION.  287 

the  products  obtained  by  the  restricted  hydrolysis  of  starch  by  malt 
diastase. 

'  This  was  a  non-crystallisable  substance,  having  definite  optical  and 
reducing  properties  corresponding  to  [a]ys^  193*1°,  and  k^^  21*1. 
Expressed  in  the  notation  now  usually  adopted,  these  values  are 
equivalent  to  [a]]>  180^.  R  34'5,  the  reducing  power  of  maltose 
being  R  100. 

The  homogeneity  of  maltodeztrin  was  proved  by  the  persistence  of 
the  above  optical  and  reducing  powers  under  eontinued  fractionation 
with  alcohol,  and  also  by  the  fact  that  it  would  pass  slowly  through 
a  dialyser  without  change.  Its  unf  ermentability  with  ordinary  yeast, 
and  the  subsequently  ascertained  fact  that  it  yields  no  crystallusable 
osazone  with  phenylhydrazine,  proved  the  absence  of  ordinary  maltose 
from  maltodeztrin. 

One  of  the  most  marked  characteristics  of  maltodextrin,  and  of  the 
amyloms  generally,  was  found  to  be  the  complete  conversion  into 
crystallisable  and  fermentable  maltose  under  the  action  of  the  very 
active  diastase  of  air-dried  malt ;  it  was  not  converted  into  a  definite 
mixture  of  maltose  and  a  comparatively  stable  dextrin  in  the  same 
way  that  soluble  starch  is  under  similar  conditions. 

In  the  paper  of  1886  above  cited,  it  was  considered  that  the  facts 
known  up  to  that  time  warranted  the  conclusion  that  the  formula  of 

maltodextrin  might  be  written  as  \    ^^  xl^  ^"^  v  ;  that  is,  as  a  com- 

bination  of  two  amylin  or  dextrin  groups  with  one  amylon  or  maltose 
group. 

Subsequent  determinations  of  the  molecular  weight  by  the  freezing 
point  method  appeared  to  confirm  this  view,  but  we  do  not  lay  much 
stress  on  this  fact,  since  we  are  now  convinced  that  the  method  of 
freezing  is  not  by  any  means  generally  applicable  to  the  non-crystal- 
lisable  products  of  starch-hydrolysis. 

The  present  paper,  together  with  the  communications  immediately 
following  it,  give  an  account  of  the  principal  results  we  have  obtained 
during  the  past  two  years  of  continuous  work  on  the  subject  of  starch- 
hydrolysis.  The  latter  part  of  the  research  has  been  carried  on  in 
the  Davy-Faraday  Research  Laboratory  of  the  Royal  Institution,  and 
we  take  this  opportunity  of  tendering  our  thanks  to  the  Directors 
and  to  Dr.  A.  Scott  for  the  facilities  they  have  given  us. 

The  methods  hitherto  employed  for  the  separation  and  examination 
of  the  starch  products  have  necessarily  been  very  limited,  and  have 
for  the  most  part  been  confined  to  (1)  a  determination  of  the  optical 
and  reducing  constants  of  the  products  after  as  complete  a  separation 
as  possible  by  alcoholic  fractionation  ;  (2)  an  inquiry  into  the  mode  of 

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288  BROWN  AND  MILLAR:   MALTODBXTRIN  : 

action  of  diastase  on  the  separate  substances ;  and  (3)  their  behaviour 
with  phenylhydrazine.  Occasionally,  attempts  have  been  made  to 
determine  the  molecular  weight  by  the  freezing  point  method,  and 
sometimes  also  the  action  of  yeast  has  been  tried,  with  or  without  the 
addition  of  diastase. 

These  methods,  which  are  necessarily  very  imperfect,  have  often 
given  different  results  in  the  hands  of  different  experimenters ;  indeed, 
so  far  is  this  the  case  that  there  may  be  said  to  be  no  unanimity  even 
as  regards  the  main  facts  of  starch-hydrolysis. 

After  turning  our  attention  to  the  improvement  of  the  existing 
methods  of  analysis  of  starch  products,  the  results  of  which  we  laid 
before  the  Society  in  1897  (Trans.,  1897,  71,  72,  109,  115,  275),  we 
endeavoured  to  supplement  the  older  methods  of  attack  with  others. 

The  one,  which  up  to  the  present  has  been  by  far  the  most  promising, 
is  based  on  a  study  of  certain  well-defined  oxidation  products  which 
can  be  obtained  from  some  of  the  non-crystallisable  starch  derivatives. 
These  are  complex  carboxylic  acids  which  are  capable  of  further 
hydrolysis  by  diastase  and  dilute  acids  respectively.  An  examination 
of  the  salts  of  these  acids,  and  a  determination  of  the  exact  amount  of 
sugars  which  they  yield  on  hydrolysis,  has  thrown  much  light  on  the 
constitution  of  the  polysaccharide  before  oxidation,  and  the  method 
appears  to  be  capable  of  considerable  extension.  In  the  present 
paper,  we  shall  confine  ourselves  to  the  study  of  the  acid  derivatives  of 
maltodextrin. 

II.  FreparcUion  of  McUtodextrin, 

The  preparation  of  maltodextrin  in  a  state  of  purity,  and  in  sufficient 
quantity  to  admit  of  satisfactory  work,  is,  in  itself,  a  difficult  matter. 
It  must  be  remembered  that  we  have  to  deal  with  an  absolutely 
unorystallisable  substance,  differing  only  very  slightly  in  solubility 
from  various  other  colloidal  substances  of  a  somewhat  similar  nature 
always  accompanying  it  in  the  mixture  of  partially  hydrolysed  starch 
products  from  which  it  has  to  be  separated  ;  it  is  only  by  long  and 
very  laborious  fractionation  with  alcohol  that  the  required  result 
can  be  attained.  If  we  commence  with  the  mixed  products  derived 
from  2000 — 2500  grams  of  starch,  we  may  consider  ourselves  fortunate 
if  we  can  obtain  350 — 370  grams  of  crude  maltodextrin,  and  this  will 
probably  be  reduced  to  from  50  to  60  grams  by  the  time  it  is  sufficiently 
purified.  Such  a  fractionation  generally  requires  from  two  to  three 
months  to  be  effectually  carried  out. 

The  mo<hu  operandi  which  we  have  found  to  answer  the  best  is  as 
follows. 

About  2  kilos,  of  well-washed  potato  starch  are  used  in  each  opera- 


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ITS  OXIDATION-PBODUCTS  AND  CONSTITUTION.  289 

tion.  Such  an  amount  of  starch,  by  the  ordinary  process  of  gelatinisa- 
tion,  which  must,  of  course,  precede  hydrolysis,  would  require  as  much 
as  50  litres  of  water,  since  a  starch-paste  of  much  more  than  4  per 
cent,  concentration  becomes  unmanageable. 

In  order  to  reduce  the  volume  of  liquid  to  a  reasonable  point,  so  as 
to  obtain  the  products  of  hydrolysis  in  a  fairly  concentrated  state,  the 
following  device  was  adopted.  Five  hundred  grams  of  the  starch,  that 
is,  one-quarter  of  the  whole  amount,  were  gelatinised  with  12  litres  of 
water  at  100°  in  the  ordinary  manner ;  the  starch-paste  so  obtained 
was  then  cooled  to  about  60°,  and  to  this  a  trace  of  malt  extract  was 
added,  just  sufficient  to  destroy  its  viscidity.  The  solution  was  once 
more  heated  to  100°  and  made  use  of  for  gelatinising  a  further  quantity 
of  the  starch,  which  was  in  turn  rendered  just  liquid  with  malt  extract 
after,  of  course,  cooling  to  60°.  These  operations  were  repeated  until 
the  whole  of  the  2000  grams  of  starch  were  obtained  in  solution  in 
from  12  to  13  litres  of  liquid.  This  was  finally  hydrolysed  to  the 
required  extent  with  an  amount  of  finely  divided  malt  equal  in  amount 
to  about  2  per  cent,  by  weight  of  the  starch  employed.* 

It  is  better  to  take  a  kiln-dried  rather  than  an  air-dried  malt  for 
this  purpose,  so  as  to  ensure  the  limitation  of  the  diastatic  action. 
We  prefer  a  malt  with  a  diastatic  power  of  about  38  according  to 
lintner's  standard.  The  temperature  of  the  transformation  should 
be  65°,  and  the  progress  of  the  reaction  must  be  followed  with  the 
polanscope,  and  arrested  by  boiling  when  the  specific  rotatory  power 
has  fallen  to  about  [ajo  168°  tot  175°. 

In  some  cases,  the  filtered  solution,  containing  about  15  percent,  of 
mixed  starch  products,  was  submitted  to  fermentation  for  a  few  days 
with  a  little  washed  yeast,  so  as  to  remove  the  greater  part  of  the 
maltose,  but,  on  the  whole,  we  prefer  to  separate  the  maltose  by 
alcoholic  fractionation  only. 

The  solution  of  mixed  products,  after  evaporation  to  a  thin  syrup, 
is  then  poured  into  about  5  litres  of  alcohol  of  90  per  cent,  (by 
volume),  which  is  reduced  to  about  87  per  cent,  by  the  water  of  the 
syrup,  and  the  mixture  is  digested  on  a  water-bath  for  some  hours  at 

*  We  luiTe  sometimes  employed  about  40  c.c.  of  a  cold-water  malt-eztract  in- 
stead of  malt.  This  is  made  by  digesting  finely  divided  malt  with  2^  times  its 
weight  of  cold  water  for  6  to  8  honrs.  The  filtered  liquid  must  be  heated  to  65° 
ior  about  15  minutes  before  it  is  used,  so  as  to  restrict  the  diastatic  power.  If  this 
latter  precaution  is  not  taken,  there  is  danger  of  running  the  hydrolytic  process 
down  too  far,  thus  reducing  the  yield  of  maltodeztrin. 

t  In  the  previous  paper  of  1885  on  maltodeztrin,  it  was  recommended  to  com- 
mence with  a  transformation  whose  united  products  has  a  specific  rotatory  power 
of  about  [a Id  180.  We  have  since  found  that  the  lower  value  mentioned  in  the 
paper  gives  the  best  yield  of  maltodeztrin. 


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290  BBOWN  AND  MILLAR:  MALTODBXTBIN  : 

the  boiling  point  of  the  alcohol,  with  frequent  agitation ;  it  is  then 
allowed  to  cool  slowly,  and  the  clear  alcoholic  liquid  poured  off  and 
distilled.  The  residue  from  the  first  digestion  is  now  treated  in  a 
similar  manner  with  successive  quantities  of  3  litres  of  alcohol  of  a 
uniform  strength  of  85  per  cent.,  each  digestion  being  continued  for 
a  whole  day.  In  this  manner,  the  original  starch  products  are  split 
up  into  15  or  20  principal  fractions,  the  early  members  of  which 
contain  most  of  the  maltose,  and  have  a  lower  specific  rotatory  power 
than  the  later  fractions.  It  is  the  intermediate  and  later  fractions 
which  contain  most  of  the  maltodextrin,  whilst  the  greater  part  of  the 
'  stable '  dextrin  is  left  in  the  residue  insoluble  in  85  per  cent,  spirit. 

The  first  three  or  four  of  the  principal  fractions  are  rejected 
entirely,  and  the  remainder,  selected  according  to  their  specific 
rotatory  power,  are  re-united  to  form  two  more  parent  fractions  for 
subsequent  treatment,  one  of  them.  A,  being  made  up  of 
fractions  with  an  [a]i>  of  from  about  164 — 173^,  and  the  other,  B, 
of  all  the  remaining  fractions  possessing  a  specific  rotatory  power 
lying  between  about  [a]©  174°  and  182°. 

Fraction  B,  which  may  amount  in  such  an  experiment  to  350  ot 
400  grams,  consists  for  the  most  part  of  a  mixture  of  various  malto- 
dextrins  with  a  little  maltose  which  is  detectable  with  phenyl- 
hydrazine.  When  treated  with  a  little  malt-extract  (from  air-dried 
malt)  at  50°  for  an  hour,  it  yields  about  94  per  cent,  of  maltose,  so 
that  the  amount  of  stable  dextrin  in  the  mixture  must  be  very  small. 

Both  A  and  B  are  further  fractionated  in  an  exactly  similar 
manner,  but  using  alcohol  of  90  instead  of  85  per  cent.  Selections 
from  the  resulting  fractions  are  again  made  according  to  optical 
activity  and  reducing  power,  and  those  are  again  united  whose  pro- 
perties approach  the  maltodextrin  sought,  a  similar  process  of  treat- 
ment being  continued  until  a  product  is  obtained  which  is  no  longer 
capable  of  being  further  differentiated  by  alcohol. 

Such  a  procedure  necessarily  occupies  a  very  long  time,  and  the 
constant  elimination  of  the  less  pure  products  results  in  a  very  small 
final  yield  of  maltodextrin. 

We  here  give,  in  diagrammatic  form,  an  example  of  one  of  many 
such  fractionations  which  we  have  made  during  the  progress  of  our 
work.  In  this  particular  case,  which  was  not  exceptional  in  any 
way,  the  complete  separation  occupied  nearly  three  months,  and 
entailed  about  sixty  separations. 


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ITS  OXIDATION-PBODUCTS  AND  CONSTITUTION. 


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292  BROWN  AND  MILLAR:  MALTODEXTBIN : 

III.  Properties  qf  Maltodextrin. 

Maltodeztrin  thus  obtained  appears  to  be  a  homogeneous  product. 
It  is  a  noD-crystallisable  syrup  which  can  only  be  completely  dried  in 
a  vacuum  over  phosphoric  anhydride  in  the  apparatus  we  described  in 
1897  (see  Trans.,  1897,  71,  76)  ;  in  this  condition,  it  is  a  colourless 
vitreous  solid,  somewhat  hygroscopic,  and  soluble  in  hot  water  to  an 
unlimited  extent.  It  is  soluble  in  alcohol  of  85  per  cent,  to  the 
extent  of  about  1  gram  per  100  c.c,  and  is  less  sparingly  soluble  in 
alcphol  of  90  per  cent. 

It  possesses  the  following  optical  and  reducing  properties.* 
[aJD  181—183° 
R  42—43 

The  above  specific  rotatory  power  agrees  very  closely  with  the 

.  observations  described  in  1885  {loc,  eit,),  but  the  reducing  power  is 

considerably  higher  than  the  value,  R  34*5,  assigned  to  maltodextrin 

in  the  earlier  work.     We  are  unable  to  account  for  this  discrepancy, 

and  must  be  content  for  the  present  merely  to  record  it. 

Maltodeztrin,  notwithstanding  its  high  reducing  power,  certainly 
does  not  contain  any  maltose  as  such,  since,  unless  previously  hydro- 
lysed,  it  is  not  in  'the  slightest  degree  fermentable  with  ordinary 
brewery  yeast,  and  it  does  not  yield  a  trace  of  crystaUisable  osazone 
with  phenylhydrazine. 

When  a  5  or  10  per  cent,  aqueous  solution  of  maltodextrin  is 
digested  for  an  hour  at  50°  with  a  few  c.c.  of  malt-extract  made 
from  air-dried  malt,  hydrolysis  proceeds  very  rapidly,  and  the  pro- 
ducts of  the  reaction  (due  correction,  of  course,  being  made  for  the 
malt-extract)  approximate  closely  in  properties  to  those  of  pure 
maltose. 

It  is  only  necessary  to  give  the  results  of  one  such  experiment, 
which  is  typical.  A  maltodextrin  of  [a]i>  181*1°  and  E  42*8,  on 
hydrolysis  under  the  above-mentioned  conditions,  gave  a  solution  with 
[aJD  141*0°  and  R  94*0,  the  properties  of  pure  maltose  for  a  similar 
concentration  being  [  a  ]d  138*0°  R  100*0.  Phenylhydrazine  now  gave 
a  large  yield  of  highly  crystalline  osazone,  which,  when  separated  from 
the  trace  of  glucosazone  due  to  the  sugars  of  the  malt-extract,  proved 
to  be  maltosazone  with  its  usual  melting  point.  The  crystals  agreed 
in  form  with  the  well-crystallised  osazone  given  by  pure  maltose,  and 
they  were  unmixed  with  the  "  isomaltosazone "  forms  which  in- 
variably occur  when  traces  of  dextrinous  impurities  are  present  (see 

*  It  will  be  noticed  that  these  values  are  not  consiBtent  with  the  "  law  of 
relation "  which  we  have  prerionsly  found  to  hold  good  between  the  optical  and 
reducing  properties  of  starch-prodacts.  We  shall  have  more  to  say  on  this  point, 
and  on  the  "law  of  relation,"  on  a  future  occasion: 


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ITS  0XIDATI0N-PB0DUCT8  AND  CONSTITUTION.  293 

Trans.,  1895,  67, 731).  These  facts  confirm  us  in  our  original  opinion 
that  maltodextrin  is  completely  resolvable  into  maltose  under  the 
influence  of  diastase,  and  the  want  of  complete  accord  of  the  optical 
and  reducing  properties  of  the  hydrolysed  maltodextrin  with  those 
of  maltose  is  no  doubt  due  to  small  errors  of  experiment  incident 
to  the  hydrolytic  process. 

When  maltodextrin  is  hydrolysed  by  treatment  with  an  ctoid,  it  is 
completely  conrerted  into  d-glucose,  whose  properties  were  identified 
by  crystallising  the  sugar  and  determining  its  optical  and  reducing 
properties. 

Evidence  that  the  final  product  of  hydrolysis  of  maltodextrin  under 
these  conditions  consists  exclusively  of  dextrose  was  obtained  in 
various  ways,  as  shown  by  what  follows. 

If  maltodextrin  is  hydrolysed  with  oxalic  acid^  and  the  excess  of 
acid  is  removed  with  calcium  carbonate,  the  optical  and  reducing  con- 
stants of  the  solution  are  consistent  only  on  the  assumption  that 
nothing  but  dextrose  is  present. 

Moreover,  when  such  a  solution  of  the  hydrolysed  products  is 
firaeiumaUf//€nnerUed,  it  is  found,  on  examining  the  solution  at  various 
intervals  during  the  fermentation,  that  the  optical  and  reducing  pro- 
perties of  the  substance  which  has  disappeared,  and  of  that  which  is 
left  at  any  stage,  conform  to  the  known  optical  and  reducing  factors 
of  dextrose. 

In  addition  to  this,  we  have  carefully  studied  the  quantitative 
relation  of  the  dextrose  formed  to  the  amount  of  maltodextrin 
hydrolysed,  in  cases  where  the  hydrolysis  has  been  carried  out  with 
oxalic  acid  under  the  standard  conditions  fully  described  in  the 
appendix  to  this  communication. 

The  dextrose  was  in  these  cases  determined  by  two  independent 
methods,  (1)  by  the  increase  in  specific  gravity  during  hydrolysis, 
and  (2)  by  the  cupric  reduction  of  the  product. 

In  this  manner,  it  was  found  that  100  parts  of  maltodextrin,  on 
complete  acid  hydrolysis,  yield  the  following  amounts  of  dextrose. 

1. — ^By  increase  of  sp.  gr.  108*7  dextrose. 

2. — By  cupric  reduction     106*0       „ 

A  maltodextrin  of   the    empirical  composition    represented    by 

{/n^*w^n^\  fiJiould,  theoretically,  be  capable  of  yielding  109  per 
cent,  of  dextrose. 

IV.  Oxidation  Of  Afaltodextrin. 

The  well  marked  reducing  power  of  maltodextrin  may  be  taken  as 
evidence  that  its  molecule  contains  the  carbonyl  group,  and  it  there- 
fore seemed  probable  that,  by  limited  oxidation,  it  would  yield  a 

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294  BROWN  AND  MILLAR:  ICALTODEXTRIN  : 

hydroxy-acid  or  acida  whcNse  careful  study  might  throw  additional 
light  on  the  constitution  of  the  parent  substance. 

The  method  which  gave  promise  of  the  best  results  was  that  of 
oxidation  with  yellow  mercuric  oxide  in  the  presence  of  baryta ;  a 
process  which,  besides  allowing  of  ready  recovery  of  the  products, 
admits  of  an  estimation  of  the  amount  of  oxygen  used  up  in  the 
reaction. 

A  known  weight  of  the  maltodextrin  was  dissolved  in  water,  and 
to  the  solution,  which  was  kept  hot  on  a  boiling  water  bath,  freshly 
precipitated  mercuric  oxide  was  added,  keeping  it  always  in  con- 
siderable excess ;  successive  portions  of  a  weighed  amount  of  crys- 
tallised barium  hydroxide  were  then  slowly  added  so  as  to  keep  the 
solution  just  faintly  alkaline.  A  portion  of  the  liquid,  filtered  off 
from  time  to  time,  was  tested  with  Fehling's  solution,  and  the  process 
was  continued  until  no  further  induction  was  apparent.  It  was 
always  found  that,  as  soon  as  the  power  of  cupric  reduction  dis- 
appeared, the  further  addition  of  b^yta  to  the  hot  neutral  liquid 
caused  a  permanent  alkalinity,  and  there  was  no  further  reduction  of 
the  mercuric  oxide.  The  weight  of  the  baryta  added  is  a  measure  of 
the  amount  of  oxygen  used  up  in  the  oxidation,  half  an  atom  of  barium 
corresponding  to  one  atom  of  oxygen,  or  to  the  production  of  one 
carboxyl  group  in  the  mixed  acids  formed. 

When  maUose  is  oxidised  imder  these  conditions,  we  have  always 
found  that  the  end  of  the  reaction  with  mercuric  oxide  corresponds 
almost  exactly  to  the  assumption  of  tkrte  atoms  of  oxygen  by  each 
molecule  of  the  sugar. 

On  reference  to  a  previous  paper  in  which  we  have  given  careful 
determinations  of  the  reducing  power  of  maltose  on  Fehling's  solution 
under  standard  conditions  (Trans.,  1897,  71,  100),  it  will  be  seen 
that  the  copper  reduced  also  corresponds  very  exactly  to  the  using 
up  of  three  atoms  of  oxygen  per  molecule  of  maltose ;  hence  there  is  a 
probability  that  the  course  of  oxidation  of  maltose  is  the  same  no 
matter  whether  we  use  Fehling's  solution  or  mercuric  oxide  and 
baryta. 

The  case,  however,  appears  to  be  different  when  we  come  to 
tnaUodeaBtrin,  If,  in  this  instance,  we  estimate  the  apparent  amount 
of  maltose  in  the  maltodextrin,  with  FehUng's  solution,  that  is,  if  we 
assume  the  maltose  constituent  of  the  maltodextrin  has  the  same 
reducing  power  on  Fehling's  solution  as  free  maltose,  then  the  amount 
of  oxygen  consumed  when  maltodextrin  is  oxidised  with  mercuric 
oxide  and  baryta  is  always  greater  than  the  calculated  amount,  in  the 
proportion,  of  about  3  to  3*72.  This  difference  may  be  due  either  to 
the  oxidation  of  maltodextrin  running  a  different  course  in  the  two 
processes,  or  to  the  fact  that  the  maltose  constituent  of  maltodextrin 

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ITS  OXIDATION-PRODUCTS  AND  CONSTITUTION.  295 

is  not  oxidised  in  the  same  manner  by  Fehling's  solution  as  is  free 
maltose. 

As  an  example  of  an  experiment  on  the  oxidation  of  maltodextrin 
with  mercuric  oxide  and  baryta,  we  may  give  the  foUowing« 

84*28  grams  of  maltodextrin  having  a  specific  rotatory  power  of 
[ajo  181  1  and  a  cupric-reducing  power  of  R  42-8  were  dissolved  in 
1000  c.c.  of  water,  and  the  solution,  after  being  heated  in  a  porcelain 
evaporating  dish  on  the  water-bath,  was  treated  with  mercuric  oxide 
and  barium  hydroxide  in  the  manner  already  described.  The  point  at 
which  further  reduction  ceased  was  very  sharply  marked,  and  corre- 
sponded to  the  consumption  of  62  grams  of  Ba(0H)2  +  SH^O,  or  3'72 
atoms  of  oxygen  for  every  molecule  of  apparent  maltose  in  the  original 
maltodextrin,  as  determined  from  the  value  of  R. 

The  decomposition  of  the  barium  salts  and  the  complete  separation 
of  the  barium,  present  certain  special  difficulties.  Attempts  to  effect 
this  by  accurate  precipitation  with  sulphuric  acid  are  only  partially 
successful,  owing,  in  the  first  place,  to  a  slight  solubility  of  the  barium 
sulphate  in  the  dextrinous  liquid,  and,  secondly,  to  the  fact  that  a 
certain  amount  of  the  precipitate  is  in  such  an  extremely  finely 
divided  state  that  it  cannot  be  removed  by  ordinary  filtration,  and 
consequently  it  is  impossible  to  accurately  hit  the  point  of  complete 
decomposition  of  the  salts. 

After  many  trials,  we  have  found  the  following  method  the  best  for 
surmounting  these  difficulties. 

The  solution  of  the  oxidised  products,  after  filtration,  is  cooled  down, 
and  a  stream  of  carbon  dioxide  is  passed  through  it  in  order  to 
neutralise  the  very  small  excess  of  baryta  present.*  The  solution  of 
the  barium  salts  of  the  organic  acids  is  then  evaporated  to  a  thin 
syrup  and  the  greater  part  of  the  barium  is  thrown  out  by  adding 
dilute  sulphuric  acid. 

The  solution  of  acids  containing  BaSO^  in  suspension  is  then  placed 
in  a  centrifugal  machine,  and  the  perfectly  clear  liquid,  still,  however, 
containing  some  barium,  is  poured  off  when  complete  separation  has 
taken  place,  and  is  again  evaporated  to  a  fairly  thick  syrup.  To  this, 
about  1  C.C.  of  strong  hydrochloric  acid  is  added,  and  then  a  fair  excess 
of  sulphuric  acid,  the  solution  being  kept  cold.  Under  these  condi- 
tions, the  barium  is  completely  thrown  out  of  solution.  A  mixture  of 
95  per  cent,  alcohol  containing  some  ethylic  acetate  is  at  once  added. 
This  precipitates  the  dextrin-like  acids,  which  are  then  dissolved  in 
a  small  quantity  of  water  and  again  thrown  out  with  alcohol  and 
ethylic  acetate.    This  process  is  repeated  until  all  traces  of  mineral 

*  In  some  cases,  the  solation  at  this  point  was  treated  with  hydrogen  sulphide  to 
remove  any  traces  of  mercury  which  might  have  passed  into  solation.  As  a  matter 
of  fiict,  however,  no  mercoric  snlphide  was  ever  obtained.  ^  . 

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296  BROWN  AND  MILLAR:  MALTODEXTRIN  : 

acids  are  removed,  when  the  aqueous  solution  can  be  finally  freed  from 
the  last  traces  of  barium  sulphate  in  the  centrifugal  machine. 

The  fractionation  of  the  acids  can  then  be  proceeded  with,  but  as 
they  are  much  more  soluble  than  the  maltodeztrin  from  which  they 
are  derived,  fractionation  with  95  per  cent,  alcohol  is  insufficient. 
Advantage  can,  however,  be  taken  of  their  insolubility  in  ethylic 
acetate,  and  of  the  fact  that  they  show  a  differential  solubility  in 
mixtures  of  ethylic  alcohol  and  the  acetate.  The  method  we  have 
usually  employed  is  treatment  of  the  crude  acids  with  successive 
portions  of  hot  alcohol  by  the  process  of  digestion  employed  in  the 
fractionation  of  the  starch  products,  and  then  precipitation  of  the 
alcoholic  solutions  with  ethylic  acetate.  By  continuing  this  treatment 
through  20 — 30  fractionations,  it  was  found  possible  to  separate  the 
deztrin-like  acids  derived  from  the  oxidation -of  maltodextrin  into  two 
series,  one,  the  more  soluble  portion,  having  a  specific  rotatory 
power  of  [a]o  176° — 179°,  and  the  other  with  a  rotatory  power  of 
[ajo  189 — 192°.  It  IS  this  second  main  fraction  with  the  higher 
rotatory  power,  and  constituting  the  larger  amount  of  product,  which 
we  have  submitted  to  detailed  examination. 

When  in  a  pure  state,  it  is  an  uncrystallisable,  dextrin-like  substance, 
having  a  specific  rotatory  power  of  [a]D  1923°,  and  without  the 
slightest  reducing  action  on  Fehling's  solution.  For  convenience,  we 
will  provisionally  refer  to  this  acid  as  maltodextrinic  acid  A, 

It  has  distinctly  acid  properties,  and  forms  a  well-defined,  uncrystal- 
lisable calcium  salt,  which  can  be  prepared  by  boiling  a  solution  of  the 
pure  acid  with  calcium  carbonate,  and  precipitating  the  salt  with 
alcohol. 

The  calcium  salt  contains  2*4  per  cent.  Oa. 

The  great  interest  attached  to  this  acid  derivative  of  maltodextrin 
lies  in  the  fact  that  it  is  hydrolysable  both  by  diastase  and  by  acids, 
giving,  with  the  enzyme,  a  definite  amount  of  matton  and  an  acid  of 
lower  molecular  weight,  whilst  by  acid  hydrolysis  it  yields  a  definite 
amount  of  dextrose  and  a  final  acid  of  still  less  complexity. 

Y.  Hydrolysis  of  Maltodextrinic  Acid  A  with  Diastase. 

Under  the  ordinary  conditions  of  hydrolysis  with  diastase,  this 
acid  yields  maltose  and  an  acid  of  lower  molecular  weight,  which  we 
shall  refer  to  provisionally  as  maUodeoBirinic  acid  B, 

The  reaction  was  studied  quantitatively  in  the  following  manner. 

A  solution  of  the  A  acid,  containing  about  5  grams  per  100  cc. 
was  digested  for  2  hours  at  50°  with  5  cc.  per  100  of  a  cold  water 
malt  extract  made  from  air-dried  malt.  The  specific  rotatory  power 
rapidly  fell  from  [a]i>  192*3°  to  [a]o  162°,  at  which  it  remained 

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ITS  OXIDATION-PRODUCTS  AND  CONSTITUTION.  297 

constant,*  the  reducing  power  simultaneously  rising  from  E.  0  to 
E.  40*0  (maltose  =100).  The  solution  gave  a  pure  maltosazone  on 
treatment  with  phenylhydrazine,  and  a  further  proof  of  the  nature 
of  the  reducing  substance  was  obtained  by  submitting  the  hydrolysed 
solution  to  fermentation  with  a  little  washed  and  pressed  yeast. 
When  the  fermentation  was  complete,  the  optical  activity  and 
reducing  power  of  the  solution  were  redetermined,  and  from  the 
differences  between  these  and  the  original  values  two  distinct  esti- 
mations of  the  sugar  fermented  [were  made,  on  the  assumption 
that  it  was  maltose.    The  results  were  as  follows. 

Grams  of  maltose 
fermented  per  100  c.c. 

Estimated  from  optical  activity 2*290 

„         „         reducing  power 2416 

The  concordance  of  these  separate  determinations  leaves  no  doubt 
that  the  reducing  substance  produced  by  the  diastasic  hydrolysis  of 
the  A  maltrodextrinic  acid  is  maltose.  The  A  acid  has,  therefore, 
yielded  40  per  cent,  of  maltose  and  60  per  cent,  of  some  other 
substance. 

VI.  MaUodextrtnic  Acid  B. 

This  can  be  isolated  from  the  products  of  the  diastase  hydrolysis  of 
the  A  acid  in  the  following  manner. 

The  mixed  products  are  fermented  as  completely  as  possible  with 
a  little  washed  yeast,  and  the  residue,  which  is  decidedly  acid  in 
character  and  amounts  to  60  per  cent,  of  the  original  A  acid,  is 
boiled  with  a  little  calcium  carbonate.  After  filtration,  the  solution  is 
evaporated,  treated  with  dilute  alcohol  to  remove  a  trace  of  proteids 
derived  from  the  yeast,  and  the  calcium  salt  is  precipitated  by  more 
alcohol ;  this  is  further  purified  by  re-dissolving  it  in  water  several 
times  and  throwing  out  by  alcohol.  At  this  point,  the  calcium  salt 
was  found  to  contain  3*1  per  cent,  of  calcium,  but  as  it  was 
not  yet  quite  pure,  it  was  submitted  to  still  further  treatment. 
The  salt  is  in  the  first  place  re-converted  into  the  free  acid  by 
exctct  precipitation  with  oxalic  acid.  To  the  solution,  filtered  from 
calcium  oxalate,  tribasic  lead  acetate  is  added,  and  after  separating  a 
small  precipitate  which  is  formed,  the  solution  is  treated  with  hydrogen 
sulphide.  The  filtrate  from  the  lead  sulphide  containing  the  acid  is 
precipitated  with  strong  alcohol,  and  the  precipitated  maltodextrinic 
acid  B  is  repeatedly  evaporated  on  the  water-bath  with  alcohol  until 
the  acetic  acid  is  completely  removed.  The  acid  is  again  con- 
It  is,  of  course,  understood  that  the  nanal  corrections  were  made  for  the  malt 

tract 

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298  BROWN  AND  MILLAB:  MALTOBEXTRIN : 

verted  into  its  calcium  salt  by  boiling  with  calcium  carbonate^  and 
the  salt  is  separated  by  alcohol  precipitation. 

It  is  a  white,  amorphous  powder  which^  after  drying  at  100*, 
contains  3*8  per  cent,  of  calcium. 

YII.  Acid  Hydrolysia  of  Maltodextrvnic  Acids  A  and  B. 

Both  A  and  B  maltodeztrinic  acids  yield  definite  amounts  of 
dextrose  on  hydrolysis  with  acid,  with  the  separation  of  a  final  residual 
acid  which  is  identical  in  the  two  cases. 

These  reactions  have  been  studied  quantitatively  by  acting  on  a 
definite  amount  of  the  acids,  or  their  salts,  with  oxalic  acid,  under 
the  standard  conditions  described  in  the  appendix.  The  amount  of 
dextrose  obtained  from  the  free  A  acid  in  this  manner  was  found 
in  one  case  to  be  85-8  per  cent.,  and  in  a  second  85*3  per  cent.  The 
calcium  gait  of  the  B  acid,  under  similar  conditions,  gave  67*7  per  cent, 
of  dextrose. 

The  sugar,  separated  from  the  hydrolysed  liquid  by  crystallisation, 
proved  to  be  ^glucose,  without  the  admixture  of  any  other  sugar.* 

VIIL  The  Final  Acid  obtained  by  the  Acid  Hydrolysis  of  Maltodextrinic 

Acids  A  and  B. 

This  acid  is,  with  simultaneous  production  of  dextrose,  the  final 
result  of  the  acid  hydrolysis  of  both  the  A  and  the  B  acids.  We  have 
obtained  it  from  both  sources,  but  it  is  of  course  more  convenient  to 
prepare  it  by  direct  acid  hydrolysis  of  the  A  acid,  without  any 
intermediate  use  of  diastase.  It  can  be  isolated  from  the  products 
of  oxalic  acid  hydrolysis  by  two  methods.  By  the  first,  the  solution, 
after  neutralisation  with  calcium  carbonate,  is,  in  the  first  place, 
fermented  to  remove  the  dextrose,  and  is  then  evaporated  and  treated 
with  strong  alcohol  to  precipitate  the  calcium  salt.  By  the  second 
method,  fermentation  is  avoided,  the  neutralised  liquid,  after  evapora- 
tion^ being  treated  with  stnmg  alcohol  for  the  removal  of  the  dextrose. 
On  the  whole^  we  prefer  to  omit  fermentation. 

The  calcium  salt  thus  obtained  is  further  purified  by  precipitation 
from  its  aqueous  solution  with  alcohol  of  95  per  cent,  with  the 
addition,  as  occasion  demands,  of  a  little  ether.  When  alcohol  alone 
is  used,  the  salt  is  apt  to  come  down  very  imperfectly  and  in  such  a  very 
finely  divided  state  that  it  remains  suspended,  forming  a  jnilky  liquid. 

*  In  one  of  these  experiments  on  the  B  calciam  salt,  the  oalciom  oxalate  which 
separated  during  hydrolysis  was  estimated.  Its  calciam  was  foand  to  correspond  to 
8*8  per  cent,  of  the  salt  taken,  a  result  which  agrees  exactly  with  the  direct  de- 
termination of  calciam  in  the  original  B  salt. 

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ITS  OXIDATION-PBODUCTS  AND  CONSTITUTION.  299 

This  milk  can,  however,  be  made  to  **  break  "  by  shaking  with  a  little 
ether.  Where  the  object  is  purity  of  product  rather  than  yield,  the 
addition  of  the  ether  should  be  as  far  as  possible  limited. 
.  The  first  preparation  of  the  calcium  salt  of  the  final  acid  from  the 
hydrolysis  of  maltodeztrinic  add  A  gave  10*1  per  cent,  of  calcium. 
By  hydrolysis  of  the  B  acid,  the  salt  was  obtained  also  containing 
lO'l  per  cent,  of  calcium.  In  the  former  case,  the  fermentation 
method  had  been  employed. 

By  very  careful  and  repeated  fractionation  of  the  calcium  salt,  a 
product  was  finally  obtained  containing  10*44  per  cent,  of  calcium,  but 
beyond  this  it  was  found  impossible  to  go. 

A  combustion  of  this  calcium  salt  with  potassium  dichromate  in  a 
stream  of  oxygen  and  air  gave  the  following  results. 

0-2148  gave  0-2666  COj  and  01004  H2O.     C  =  324  ;  H  =  51. 
{G^^fi^\C2k  requires  0  «  324 ;  H  =  4*9  ;  Ca  =  108  per  cent. 

The  study  of  this  acid  has  been  much  facilitated  by  the  discovery 
that  the  same  final  acid  is  present  in  considerable  quantity  amongst 
the  products  of  oxidation  of  malta$e  by  mercuric  oxide  and  baryta. 
The  oxidation  of  maltose  was  carried  out  in  exactly  the  same  manner 
as  that  of  maltodextrin  already  described.  The  calcium  salts  of  the 
acids  obtained  were  hydrolysed  with  oxalic  acid,*  and  the  final  acid 
was  purified  as  a  calcium  salt  in  exactly  the  same  manner  as  the  final 
acid  from  the  hydrolysed  maltodextrinic  acids. 

In  this  state,  two  preparations  gave,  after  drying  at  100%  percent* 
ages  of  calcium  equal  to  10*4  and  10*5  respectively. 

The  latter  preparation,  on  combustion  with  dichromate,  gave  the 
following  results. 

I.  0-2636  gave  0-3023  COg  and  01161  HgO.     0-324  ;  H«50. 
11.0*2131     „    0-2621  COj    „    00964  HjO.    0  =  32-2;  H  =  60. 
(05HgO^)30a  requires  0  «  32  4 ;  H  =  4-9 ;  Oa  =  10'8  per  cent. 

There  can  be  no  question  as  to  the  identity  of  the  final  acids  ob- 
tained by  the  oxidation  and  hydrolysis  of  maltodextrin  and  maltose 
respectively,  as  both  their  properties  and  their  percentage  composition 
are  similar. 

The  acid  itself,  when  liberated  from  its  calcium  salt,  is  a  colourless 
syrup  which  shows  no  tendency  to  form  a  crystallised  lactone.  It  is 
very  soluble  in  water,  but  almost  insoluble  in  alcohol  of  96  per  cent. 

*  Daring  this  hydrolysis,  considerable  quantities  of  dextrose  were  liberated.  The 
oxidation  of  maltose  under  the  above  conditicms  evidently  results  in  the  production 
of  biose  acids  which  are  resolvable  on  hydrolysis  into  C«-  and  Cp-groups.  We  are 
sabmittiBg  this  interesting  fact  to  dose  examination. 


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300  BROWN  AND  MILLAB :  MALTODEXTRIN  : 

Its  cinchosic  salt  shows  no  tendency  to  crystaUise^  but  the  acid 
appears  to  form  a  orystallisable  hydrazide,  the  only  crystalline 
derivative  we  have  been  able,  np  to  the  present,  to  prepare.  The 
caloinm  salt  is  very  soluble  in  water,  but  quite  uncrystallisable  from 
that  solvent ;  it  has  only  a  very  slight  influence  on  polarised  light, 
and  the  actual  amount  of  rotation  is  still  doubtful. 

The  great  obstacle  to  the  extended  examination  of  this  acid  has 
hitherto  been  the  difficulty  of  its  preparation  in  sufficient  quantity ; 
now,  however,  that  its  identity  with  the  acid  similarly  obtained  from 
maltose  is  put  beyond  all  doubt,  we  shall  be  able  to  prepare  it  in  con- 
siderable quantities  and  submit  it  to  a  careful  study. 

Taking  into  consideration  the  method  of  its  formation,  its  source, 
and  the  empirical  formula  of  its  calcium  salt,  it  would  appear  to  be  a 
normal  carboxylic  acid  derived  from  a  pentose.  It  has  certain  pro- 
perties in  common  with  xylonic  acid  produced  by  the  oxidation  of 
xylose,  but  our  detailed  study  of  the  acid  in  question  is  at  present 
too  incomplete  for  us  to  speak  positively  on  this  point.  It  appears  to 
us,  however,  that  the  preparation  of  a  Gg-derivative  from  a  C|2-<sarbo- 
hydrate  in  the  manner  we  have  described  is  an  interesting  fact,  and 
that  in  the  limited  oxidation  and  hydrolysis  of  polysaccharides  of  C^- 
sngars  we  may  have  an  approach  to  an  explanation  of  the  formation 
of  pentose  derivatives  by  living  plants. 

In  connection  with  this  subject,  we  are  also  reminded  of  O'SuUivan's 
work  on  the  arabinic  acids  (Trans.,  1884,  46,  41 ;  1890,  67,  59  ; 
1891,  60,  1029),  in  which  he  showed  that  arabic  acid  under  the 
hydrolysing  influence  of  dilute  sulphuric  acid  yielded  a  series  of  acids 
of  gradually  diminishing  molecular  weight  with  simultaneous  produc- 
tion of  arabinose  and  in  some  cases  galactose. 

IX.  Constitution  of  the  MaUodexirinic  Adda  and  Maltodextrvn. 

From  its  mode  of  preparation,  and  its  behaviour  under  successive 
hydrolysis  with  diastase  and  oxalic  acid,  it  is  clear  that  maltodex- 
trinic  acid  J[,  the  main  product  when  maltodextrin  is  oxidised  with 
mercuric  oxide  and  baryta,  must  be  a  carboxylic  acid  derived  from  a 
polysaccharide.  Since  the  original  polysaccharide,  maltodextrin,  is  a 
reducing  substance  completely  hydrolysable  to  maltose  by  diastase, 
it  must  be  regarded  as  being  made  up  of  a  certain  number  of  C^g  or 
maltose  residues  with  the  elimination  of  the  elements  of  water,  but 
still  retaining,  like  maltose  itself,  a  terminal  COH  group.  If  the 
process  of  oxidation  of  the  polysaccharide  consisted  merely  in  the 
transformation  of  this  terminal  GOH  into  carboxyl,  we  should  expect 
to  obtain  an  acid  with  its  terminal  C^^'fi^^P  ^^^  ^P  ^^  ^^^  malto- 


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ITS  OXIBATION-PRODUCTS  AND  CONSTITUTION. 


801 


bionic  acid  type.*  Such  an  acid,  when  treated  with  oxalic  acid,  would, 
like  maltobionic  acid,  be  transformed  into  glucose  and  gluconic  acid, 
whilst  under  the  action  of  diastase  it  would  be  almost  certain  to  yield 
maltose  and  free  maltobionic  acid. 

Although  it  is  very  probable  that  under  the  oxidising  influence  of 
bromine^  maltodextrin  may  ultimately  yield  a  complex  acid  of  this 
constitution,  it  is  evident  that  when  mercuric  oxide  and  baryta  are 
used  the  oxidation  proceeds  much  farther,  and  results  in  the  splitting 
up  of  the  terminal  Cj^^-group  into  a  C^-acid  residue  which  remains 
attached  to  the  hydrolysable  portion  of  the  polysaccharide,  and 
adds  of  low  molecular  weight  which  are  separable  by  the  sub- 
sequent treatment  to  which  the  complex  acid  is  submitted  during 
purification. 

It  has  been  shown  by  Scheibler  and  Mittelmeier  (Ber,,  1890,  23, 
3060;  ibid.,  1893,  26,  2930)  that  the  formation  of  reducing  poly- 
saccharides, that  is,  of  compound  saccharides  with  an  aldose  or  ketonic 
structure  of  the  terminal  group,  may  be  explained  by  the  union,  with 
elimination  of  the  elements  of  water,  of  the  carbonyl  of  one  of  the 
constituent  groups  with  an  alcohol  group  of  another. 

If  we  accept  Fischer's  constitutional  formula  for  maltose  as 

CH2(OH)-CH(OH)-CH-[CHOH]2-CH-0-CH2-[CHOH]^-COH, 

\ O / 

a  polysaccharide  corresponding  to  the  empirical  formula  <  >,  ^no       * 

which  we  have  hitherto  employed  for  maltodextrin,  will  be  repre- 
sented by  the  union  of  three  molecules  of  maltose,  in  the  manner 
described  above,  with  the  elimination  of  2  mols.  of  water.  The 
constitutional  formula  of  maltodextrin  may  then  be  represented  as 
follows. 


CHOH 
<[CHOH], 


I 


o 


H, 
CHOH 
OH 


0<^[OHOH], 
^OH 


OH, 

OHOH 
/OH 
0<^[CHOH], 
^OH 
0 

OHj 
OHOH 
/OH 
0^[OHOH], 


'OH 


OH, 

OHOH 
/OH 
0<'[OHOH], 
^OH 
O 

OH, 

[OHOH]^ 
COH 


*  Maltobionic  acid,  OuHgOj^  was  obtained  by  E.  FiBcher  and  Hcyer  by  the 
oxidation  of  maltose  with  bromine  {Ser.,  1889,  22, 1943).  From  the  fact  that  it 
splits  np,  nnder  the  inflaence  of  dilnte  mineral  add,  into  <i-glacose  and  <i-glaoonio 


VOL.  LXXY. 


,.gitized  by 


Gijt„ 


BROWN  AND  MILLAR:  KALTODRXTRIN : 
This  may  be  written  in  an  abbreviated  form  thns, 

The  <[  IB  used,  as  suggested  bj  Scheibler  and  Mittelmeieri  to 
denote  the  open  terminal  COH-groap.  In  this  scheme,  the  (\f- 
groups  are  represented  as  linked  to  one  another  through  oxygen 
atoms,  and  it  is  at  these  points  that  the  elements  of  2  mols.  of  water 
are  introduced  during  diastase  hydrolysis,  with  the  formation  of 
3  mols.  of  maltose. 

When  the  hydrolytic  agent  is  an  acid,  the  complex  molecule 
behaves  as  though  it  were  made  up  of  O^^-groups,  also  linked  through 
the  intermediary  of  an  oxygen  atom,  and,  just  as  in  the  former 
case,  it  is  at  these  points  that  the  elements  of  water  are  introduced, 
with  the  consequent  production  of  glucose.  Maltodextrin  should 
therefore  take  up  the  elements  of  6  mols.  of  water  in  order  to  be 
completely  converted  into  glucose,  100  parts  of  maltodextrin  yielding 
109  of  dextrose.  How  near  this  conclusion  corresponds  to  the  facts 
has  already  been  shown  (p.  293). 

It  may  be  objected  that,  according  to  the  above  constitution  of 
maltodextrin,  there  seems  to  be  no  sufficient  reason  why  diastase  and 
acids  should  not  both  hydrolyse  it  to  glucose,  since,  constitutionally 
considered,  there  is  no  apparent  difEerence  between  the  linkings  of  the 
C^-and  0^12*^^^?^* 

There  may,  however,  be  a  difference  of  spatial  relations  between 
the  adjacent  Oj^^-groups  which  may  be  sufficient  to  determine  the 
differential  action  of  the  diastase,  as  contrasted  with  the  absence  of 
that  action  on  the  constituent  Cg-groups,  where  we  have  every 
reason  to  believe  the  configuration  is  identical* 

Another  possible  explanation  may  be  found  in  the  relative  size  or 
mass  of  the  G^-  and  Cig'S^^^P^'  which  may  have  some  effect  on  the 
result.  We  have  probably  an  instance  of  this  kind  in  the  selective 
effect  qt  the  enzyme  glucase  on  a-methyl-><2-glucoside  on  the  one  hand, 
and  a-methyl-xyloside  on  the  other,  as  shown  by  Fischer  (Z0U. 
phynol.  Chem.,  1898,  26,  68). 

Of  these  two  glucosides,  one  derived  from  a  C^-  and  the  other  from 
a  Cg-sugar,  and  built  up  on  an  exactly  similar  plan,  both  constitu- 

acld,  the  concltuiion  was  drawn  that  maltobionio  aoid  is  derired  from  maltose  by 
the  oxidation  of  the  terminal  COH-groap. 

We  have  onraelyes  prepared  maltobionio  acid  in  the  above  manner,  and  hare 
studied  its  products  of  hydrolysis  qoantitatively.  These  results  which  will  be 
found  described  in  the  appendix  to  this  paper,  are  fully  confirmatoiy  of  the  oon- 
elusions  of  Fischer  and  Meyer. 


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ITS  OXIBATION-PRODUCTS  AND  CONSTITUTION.  303 

tionallj  and  stereochemicallj,  the  derivative  of  ^glucose  is  readily 
attacked  by  glucase,  whilst  that  of  xylose  resists  the  action  of  the 
enzyme.  The  same  difference  also  exists  between  the  action  of  emulsin 
on  the  )9-methyl-c{-glucoside,  and  the  )3-methyl-xyloside  respectively. 

Possibly  an  investigation  which  we  are  making  on  the  influence  of 
the  two  enzymes,  glucase  and  diastase,  on  maltodextrin  may  deter- 
mine which  of  the  above  explanations  is  probable. 

If  the  oxidation  of  maltodextrin  resulted  merely  in  the  conversion 
of  the  GOH-group  into  carboxyl,  an  acid  would  be  formed  the  con- 
stitution of  which,  written  in  the  abbreviated  form,  would  be  re- 
presented as  follows. 


This  would  be  the  acid  already  referred  to,  which  would  almost 
certainly  split  up  into  maltose  and  maltobionic  acid  under  the  action 
of  diastase,  and  into  c^glucose  and  ^gluconic  acid  when  hydrolysed 
with  oxalic  acid. 

The  constitution  of  maltodextrinic  acid  A  certainly  cannot  be 
represented  in  this  manner,  for  it  yields  a  C^-acid  on  complete 
hydrolysis,  not  gluconic  acid.  The  only  explanation  possible  is  that, 
daring  oxidation  with  mercuric  oxide  and  baryta,  the  terminal  0^2" 
group  is  attacked  in  such  a  manner  as  to  remove,  by  simultaneous 
or  successive  oxidations,  (\B.^fi^f  leaving  the  residue  of  a  CgH^^OQ 
acid  still  in  combination  with  the  polysaccharide  residue.  The  only 
possible  constitution  of  the  maltodextrinic  acid  A,  and  the  only  one 
which,  as  we  shall  presently  see,  is  in  consonance  with  all  the  known 
facts,  is,  the  following, 

0<;^i2^2i^io 


The    reducing  C^j'^^^P  shown    in    the    extended    constitutional 
formula  of  maltodeictrin  has  in  fact  now  become 

-^0-CHj;[CH-OH]e-OOOH, 

which  is  the  resi(kie  of  a  normal  carboxylic  acid  derived  from  a  pentose. 
When  the  maltodextrinic  acid  A  is  hydrolysed  with  diastase  (I),  and 
with  oxalic  acid  (II),  the  reactions  take  the  following  course. 

Maltodextrinic  Maltodextrinic         Maltose. 

acid  A,  acid  B, 


Digitized  by 


G®(3gle 


304  BBOWN  AND  MILLAB:  HALTODEXTRIN  : 

n.    fC:0,,^0,    +   4H,0   =   40aH,,0,  +  CsHioO.. 

Malt«deztrinic  cf-Qlacose.         Pentose  acid, 

acid  A. 

In  a  Bimilar  manner^  the  B  acid  is  also  split  up  into  glucose  and  the 
pentose  acid  under  the  action  of  oxalic  acid,  with  the  assumption  of 
only  2  mols  of  water. 

A  careful  examination  of  the  facts  which  we  have  recorded  in  the 
experimental  part  of  this  paper  will  show  that  they  are  fully  in  accord 
with  the  above  generalisations,  as  regards  the  composition,  constitu- 
tion, and  reactions  of  the  derivative  acids.  This  is  brought  out  more 
clearly  in  the  following  summary. 

A  Acid, — The  calcium  found  in  the  purified  salt  was  2*4  per  cent., 
which  agrees  exactly  with  the  percentage  of  calcium  in  a  salt  of  the 
composition  {0^^4902q)20&,  the  empirical  formula  for  the  salt  of 
maltodextrinic  acid  A. 

On  hydrolysis  with  diasUue,  the  A  acid  gave,  in  two  experiments, 
40*0  per  cent,  of  maltose.     The  reaction  I  requires  42  per  cent. 

On  complete  hydrolysis  with  oxalic  acid,  the  A  acid  yielded,  in  one 
experiment,  85*8  per  cent,  of  glucose,  and  in  another  85*3  per  cent. 
The  reaction  II  requires  88*4  per  cent. 

jB  Acid, — ^The  calcium  found  in  the  pure  salt  was,  in  two  separate 
preparations,  3*8  per  cent.  A  salt  of  the  composition  (Oi7H^Oj0)2Ca, 
the  empirical  formula  of  the  B  salt,  should  contain  3*9  per  cent,  of 
calcium. 

The  B  calcium  salt,  on  complete  hydrolysis  with  oxalic  acid,  yielded 
67*7  per  cent,  of  glucose.     Its  theoretical  yield  is  70*7  per  cent. 

As  to  the  empirical  formula  of  the  final  C5  acid,  obtained  by  the 
complete  hydrolysis  of  the  maltodextrinic  acids,  there  can  be  no  doubt ; 
but  further  investigation  is  necessary  before  we  can  positively  state 
whether  it  is,  as  its  mode  of  preparation  would  suggest,  a  normal 
carboxylic  acid  of  a  pentose. 

The  evidence  as  to  the  constitution  of  maltodextrin  afforded  by  a 
study  of  its  oxidation  products  seems  to  us  conclusive,  and  it  is  further 
strengthened  by  the  fact  of  the  complete  hydrolysis  of  maltodextrin 
to  maltose  under  the  influence  of  diastase,  and  by  its  yielding,  within 
the  experimental  limits  of  error,  the  theoretical  amount  of  glucose  on 
treatment  with  oxalic  acid. 

This  further  study  of  the  subject  has  served  only  to  strengthen 
our  previous  views  of  the  constitution  of  maltodextrin,  although  we 
must  admit  that  some  of  the  older  evidence,  such  as  that  derived  from 
the  relation  of  optical  activity  to  reducing  power,  and  the  molecular 
weight  determinations,  was  not  such  as  we  should  now  deem  conclusive. 

Digitized  by  VjOOQIC 


ITS  OXIDATION-PRODUCTS  AND  CONSTITUTION.  305 

We  may  still,  if  we  choose,  regard  inaltodeztrin  empirically  as  a 
combination  of  an  amylon  group  with  two  amylin  groups,  and  write 

its  formula  as  |  j^i^^^i^^^^  but  we  think  that  the  new  light  we 

have  now  been  able  to  throw  on  the  subject  justifies  us  in  adopting 
another  method  of  statement  which  is  more  in  accord  with  our  ordinary 
views  of  the  structure  of  the  more  simply  constituted  carbohydrates. 
This  formula  in  its  abbreviated  form  is 

Maltodextrin. 

Appendix. 
Acid  Hydrolysis  of  Starch  Derivaiives, 

An  accurate  determination  of  the  amount  of  maltose  or  of  glucose 
which  a  starch  derivative  will  yield  on  complete  hydrolysis  with 
diastase  and  acid  respectively  is  of  great  importance  in  determining 
the  nature  and  constitution  of  the  derivative.  We  have  so  frequently 
had  occasion  to  describe  minutely  the  method  of  procedure  in  the 
case  of  diastase-hydrolysis,  and  the  processes  for  estimating  the 
products,  that  it  is  quite  unnecessary  to  enter  again  into  details  on 
this  point.  In  the  course  of  our  more  recent  investigations,  however, 
it  became  necessary  to  make  frequent  use  of  acid  hydrolysis  with 
estimation  of  the  dextA^ose  formed,  and  we  had  consequently  to  determine 
the  best  conditions  under  which  such  experiments  could  be  carried 
out,  and  the  magnitude  of  the  experimental  errors. 

An  estimation  of  dextrose  when  unmixed  with  any  other  optically 
active  or  reducing  substance  is  now  capable  of  being  conducted  with 
a  high  degree  of  accuracy.  For  the  actual  methods^of  estimation,  we 
must  refer  to  two  of  our  recent  papers  in  this  Journal  (Trans.,  1897, 
71,  72  and  275). 

If  we  have  a  substance,  such  as  a  starch  derivative,  which  is  com- 
pletely transformed  into  dextrose  by  the  acid  treatment,  we  have  three 
different  and  independent  methods  of  determining  the  dextrose  formed : 
(1)  by  observing  the  increase  in  the  specific  gravity  of  the  solution 
after  hydrolysis  and  making  up  to  the  original  volume ;  (2)  by  the 
alteration  in  the  optical  properties  of  the  liquid ;  and  (3)  by  the 
increase  in  cupric-reducing  power.  Theoretically,  these  three  methods 
should  give  identical  results,  practically  it  was  found  that  there  are 
certain  small  difEerences  which  had  to  be  determined  and  corrected  for. 

One  of  the  difficulties  met  with  at  the  outset  is  that  attendant  on  the 


806  BROWN  AND  MILLAR:  MALTODEXTRIN  : 

production  of  more  or  less  of  r&version  produotSy  which  invariably  tend 
towards  a  loss  of  reducing  power,  and  to  a  smaller  extent  of  optical 
activity.  If  ^these  reversion  products  do  not  exceed  about  5  per 
cent,  in  amount  they  have  very  little  influence  in  altering  the 
specific  gravity,  since  their  solution  density  is  very  nearly  that  of 
dextrose. 

Our  first  endeavour  was  to  find  a  means  of  hydrolysis  which  would 
ensure  complete  conversion  of  the  polysaccharides  into  dextrose  with 
the  minimum  production  of  reversion  products,  and  then  to  determine 
as  far  as  possible  the  corrections  fiecessary  for  these  under  certain 
standard  conditions  of  hydrolysis  as  regards  strength  of  acid, 
temperature  of  conversion,  and  time.  After  a  considerable  number 
of  trials,  with  careful  observations  on  the  course  of  the  reaction, 
we  finally  settled  on  the  following  standard  conditions. 

A  solution  of  the  carbohydrate  under  experiment,  of  a  concentration 
of  from  8  to  10  per  cent.,  is  hydrolysed  with  2*6  grams  per  100  c.c.  of 
crystallised  oosalie  acid.  The  solution  is  contained  in  a  pressure  flask 
immersed  in  a  boiling  water  bath,  and  the  digestion  is  carried  on  at 
100°  for  14  hours. 

In  determining  the  sp.  gr.  of  the  hydrolysed  solution,  this  must,  of 
course,  be  corrected  for  the  amount  of  oxalic  acid  present,  but  it  is 
generally  better  to  first  remove  this  from  the  hydrolysed  solution 
with  calcium  carbonate,  evaporating  somewhat,  and  making  up  to  the 
original  volume.* 

When  a  definite  amount  of  pure  dextrose  is  treated  in  this  manner, 
and  the  greatest  precautions  are  taken  to  ensure  accuracy  in  the  cupric 
reduction  experiments  and  in  the  weights  and  volume  of  the  solutions, 
the  dextrose  determined  by  cupric  reduction  after  digestion  with  the 
acid  for  14  hours  falls  short  of  the  amount  taken  by  about  5  per  cent. 
In  one  such  experiment,  where  9*309  grams  of  dextrose  were  taken, 
8*923  grams  were  estimated  in  the  hydrolysed  liquid,  a  loss  of  4*2  per 
cent.  In  another  experiment,  8*550  grams  of  dextrose  before  acid 
treatment  were  estimated  as  8*187  grams  afterwards,  a  loss  of  4*3 
per  cent. 

This  apparent  loss  is  due  to  the  formation  of  reversion  products 
which  have  a  lower  cupric  reduction  than  dextrose.  Since  we  know  that 
these  products  have  a  higher  optical  activity^than  dextrose,  we  should 
naturally  be  prepared  to  find  a  slight  increase  in  specific  rotation. 
This  was,  in  fact,  the  case.  The  specific  rotation  of  the  dextrose  in  the 
first  case  increased  from  [a][>  52*6°  to  [aj^  53*2°,  and  in  the  second 
from  [a]D  52*7  to  [a]i>  53-0. 

*  In  snoh  experiments,  the  yolnmes  are  always  deduced  from  the  weighings  and 
density.  ^  j 

Digitized  by  VjOOQIC 


I. 

II. 

III. 

IV. 

109-4 

110-9 

110-3 

— 

1110 

109-3 

— 

110-8 

110-8 

110-1 

— 

110-4 

ITS  OXIDATION-PBOBUCTS  AND  CONSTITUTION.  307 

On  the  other  hand,  there  was  no  apparent  change  in  the  sp.  gr.  of 
the  solutions  before  and  after  heating  with  the  acid. 

With  these  facts  in  view,  it  is  possible  to  apply  certain  corrections 
to  the  results  obtained  when  carbohydrates  are  hydrolysed  under  the 
standard  conditions  we  have  described.  It  must  be  understood  that 
these  corrections  have  been  applied  to  the  results  which  follow. 

Hydrdyais  of  MdUost  (anhydrous). 

Dextrose  produced  from  100  parts  of  maltose. 

1 — ^By  specific  gravity 104-8. 

2 — ^By  cupric  reduction    103*71. 

3 — ^The  theoretical  yield  of  dextrose  from 

100  parts  of  CigHj^On  is 105*26. 

Hydrolysis  qf  SohMe  Starchy  ^^e^io^s* 

1 — By  specific  gravity 
2 — ^By  optical  activity 
3 — By  cupric  reduction 

The  soluble  starch  used  in  these  experiments  was  submitted  to  a 
preliminary  drying  at  80°,  and  accurately  weighed  quantities  of  this 
were  used  for  hydrolysis,  the  amount  of  water  left  in  the  preparation 
being  determined  by  drying  over  phosphoric  anhydride  in  the  vacuum 
apparatus  at  102 — 106°.  The  volumes  of  the  solutions  were  deduced 
from  the  weights  and  specific  gravity. 

In  experiments  I  and  II,  the  determinations  were  made  on  the 
hydrolysed  solutions  still  containing  the  oxalic  acid.  Expt.  lY 
gives  the  results  of  a  further  examination  of  II,  after  removal  of  the 
oxalic  acid  with  calcium  carbonate. 

The  theoretical  yield  of  dextrose  from  100  parts  of  nQ^^fi^  is 
1111. 

EydrolysiB  of  MaUodeaOrin,  Q^^HaoO^  . 

The  results  of  this  experiment  have  been  already  given  in  the  body 
of  the  paper,  but  are  here  reproduced  for  purposes  of  comparison. 
Dextrose  yielded  by  100  parts  of  maltodextrin. 

1— By  optical  activity 108-7 

2 — By  cupric  reduction  106*0 

The  theoretical  yield  is  109  of  dextrose. 

Digitized  by  VjOOQIC 


308       BROWN  AND  MILLAR :  ATTEMPTS  TO  PREPARE  PURE 

Hyd/rolysia  of  MaUobionic  Acid, 

The  test  experiments  on  the  hydrolysis  of  maltose  and  soluble 
starch  show  that  the  method  gives  results  of  a  considerable  degree  of 
accuracy  when  certain  corrections  are  applied  which  are  constant 
under  the  standard  conditions  of  experiment.  It  was  felt  desirable, 
however,  to  test  the  method  also  on  an  acid  derivative  of  a  poly- 
saccharide which  has  some  sort  of  relation  to  the  maltodextrinic  acids 
we  have  described.  For  this  purpose,  we  prepared  maltobionic  acid  by 
the  oxidation  of  maltose  by  bromine,  as  described  by  Fischer  and 
Meyer  {loc.  cit,).  Having  prepared  the  lead  salt,  this  was  purified  as 
far  as  possible  by  frequent  precipitation  from  its  aqueous  solution  by 
alcohol,  then  decomposed  by  hydrogen  sulphide,  and  the  free  acid 
converted  into  the  calcium  salt.  The  calcium  maltobionate  was  then 
purified  still  further  by  frequently  precipitating  with  alcohol  until  its 
composition  was  constant. 

Calcium    in    pure  salt,   5*4   per  cent.,  against  5*3   required  by 

On  hydrolysing  a  definite  weight  of  the  dry  calcium  salt  with 
oxalic  acid,  under  the  standard  conditions,  we  obtained  in  one  experi- 
ment a  yield  of  41  '6  per  cent,  of  glucose,  and  in  a  second  experiment 
42-6  per  cent.  The  theoretical  yield  of  glucose  from  {0i^^\0^^jd9k 
on  complete  hydrolysis  is  47*7  per  cent. 

Dayt-Fabaday  Resbabch  Laboratory, 
Royal  Institution. 


XXXL — Attempts  to  Prepare  Pure  Starch  Derivatives 
Through  their  Nitrates, 

By  Horace  T.  Brown,  LL.D.,  F.R.S.,  and  J.  H.  Millar. 

The  comparative  ease  with  which  certain  nitrated  derivatives  of 
carbohydrates  can  be  obtained,  and  the  ready  manner  in  which  the 
NOg-groups  can  be  subsequently  removed  by  treatment  with  ammonium 
sulphide,  induced  us,  some  time  ago,  to  turn  our  attention  to  a 
method  which  we  hoped  could  be  made  applicable  to  the  separation 
of  the  dextrins  or  maltodextrins  which  occur  in  restricted  starch 
transformations  by  diastase.  These  substances  differ  so  little  in 
their  relative  solubility  in  alcohol  of  various  strengths  that  the 
ordinary  modes  of  separation  are  extremely  tedious  and  difficult. 
The  two  important  points  to  consider  were  the  degree  of  ease  with 
which  the  nitrates  could  be  fractionated  by  treatment  with  various 


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STARCH  DERIVATIVES  THROUGH  THEIR  NITRATES.         309 

solvents,  and  how  far  one  could  be  sure  that  the  recovered  product 
obtained  by  the  ammonium  sulphide  method  represented  the  original 
substance  before  nitrification. 

Although  our  hopes  have  only  been  partially  realised^  the  work  has 
not  been  without  practical  value,  since  by  its  aid,  as  will  be  seen  in 
the  following  paper,  we  have  obtained  some  indirect  evidence  as  to 
the  nature  of  the  '  stable '  dextrin  of  starch  transformations. 
Apart  from  this  comparatively  small  result,  we  believe  that  the  work 
should  be  put  on  record  as  a  guide  to  others  who  may  be  induced, 
like  ourselves,  to  give  a  considerable  amount  of  time  to  a  subject 
which  at  the  outset  looks  a  promising  one. 

It  is  only  by  applying  the  method  of  nitration  and  recovery  to 
starch  derivatives  of  well-defined  properties  that  we  can  hope  to  test 
its  value.  We  have  consequently  applied  it  to  (1)  soluble  starch, 
(2)  the  *  stable  *  dextrin  after  purification  with  alcohol,  (3)  amylo- 
dextrin,  (4)  maltodextrin,  and  (5)  maltose. 

Miration  a/nd  Recovery  qf  Soluble  Starch, 

The  soluble  starch  was  carefully  prepared  from  potato  starch  by 
lintner's  acid  process.  Twelve  grams  were  nitrated  at  0^  with  70  c.c. 
of  strong  nitric  acid,  and  the  nitrate  was  precipitated  in  the  first 
place  with  70  c.c.  of  strong  sulphuric  acid,  and  afterwards  with  water. 
It  was  purified  by  dissolving  it  in  ether  and  precipitating  with 
chloroform.     Analysis  of  the  product  by  Lunge's  method  showed 

1. — 9*3  per  cent,  of  nitrogen.  2. — 9'1  per  cent,  of  nitrogen. 

The  trinitrate  of  the  empirical  formula  022^17^7(^^8)3  i^^^ures 
91  per  cent,  of  nitrogen. 

Soluble  starch  was  recovered  from  this  nitrate  by  treating  it  at 
70^ — 80%  with  water  containing  a  little  ammonium  sulphide,  and  pass- 
ing through  the  liquid  a  stream  of  hydrogen  sulphide ;  under  these 
conditions,  the  nitrate  gradually  dissolves  with  separation  of  sulphur, 
which,  however,  again  goes  into  solution  in  an  excess  of  hydrogen 
sulphide.  The  clear  solution  was  then  heated  to  the  boiling  point 
and  the  precipitated  sulphur  filtered  off,  using  a  hot  funnel.  When 
the  concentrated  filtrate  was  treated  with  an  equal  volume  of  90 
per  cent,  alcohol,  a  thick,  slightly  discoloured,  flocculent  precipitate 
was  thrown  down ;  this  was  re-dissolved  in  water  and  again  precipi- 
tated with  alcohol,  the  process  being  repeated  several  times  until  the 
product  was  obtained  as  a  perfectly  white,  amorphous  powder.  The 
recovered  starch  had  all  the  physical  properties  of  ordinary  soluble 
starch,  giving  the  same  pure  deep  blue  colour  with  iodine.  Its 
specific  rotatory  power  was  [  a  ]i>  201*2°. 

Digitized  by  VjOOQIC 


310       BROWN   AND  MILLAR  :  ATTEMPTS  TO  PREPARE  PURE 

When  a  portion  of  this  recovered  starch  was  hydrolysed  with  malt 
extract  at  56^,  it  behaved  exactly  as  ordinary  soluble  starch  does,  the 
mixed  products  of  transformation  having  a  specific  rotatory  power  of 
[a]]>  151*8  and  a  cupric-reducing  power  of  B  76*4. 

The  recovered  product  is,  in  fact,  ordinary  soluble  starch  in  a  state 
of  great  purity,  and  absolutely  free  from  ash. 

This  process  for  the  preparation  of  soluble  starch  can  be  recom- 
mended when  a  very  pure  specimen  is  required. 

NiiraUon  a/nd  Attempted  Recovery  of  the  StaNe  Dextrin, 

The  dextrin  from  which  these  preparations  were  made  was  obtained, 
as  described  in  the  next  paper  (Trans.,  75,  p.  317),  by  repeated  alcoholic 
treatment  of  starch  products  hydrolysed  to  the  lowest  possible  point 
by  diastase.  It  is  the  stable  dextrin  of  the  so-called  ''No.  8 
equation,"  frequently  referred  to  in  our  previous  papers.  The  pro- 
perties of  this  dextrin  will  be  fully  described  in  a  following 
communication.  It  was  finally  obtained  with  the  following  optical 
and  reducing  values  :  [a]D  195*0 ;  R  5*5. 

On  treatment  with  nitric  acid,  exactly  as  described  in  the  case  of 
soluble  starch,  this  dextrin  yielded  a  nitrate  in  the  form  of  a  per- 
fectly white  powder,  insoluble  in  water,  but  soluble  in  alcohol  and 
ether  or  in  a  mixture  of  the  two  solvents.  From  such  solutions,  it  is 
completely  precipitable  by  chloroform.  Fractionation  of  the  product 
showed  that  it  must  be  a  mixture,  since  it  was  divisible  into  two 
portions  containing  10*1  and  9*36  percent,  of  nitrogen  respectively. 

Assuming  the  dextrin  to  have  a  composition  corresponding  to 
nC^HjQOg,  its  di-,  tri-,  and  tetra-nitrates  would  require  the  following 
percentages  of  nitrogen. 

Dinitrate    6*7  per  oent.  N. 

Trinitrate  9*1       „      ,, 

Tetranitrate  11*1       „       „ 

It  now  remained  to  be  seen  if  the  original  dextrin  could  be 
recovered  from  the  mixed  nitrates  by  applying  the  ammonium 
sulphide  process,  which  had  been  so  successful  in  the  case  of  soluble 
starch. 

Owing  to  the  recovered  dextrin  requiring  stronger  alcohol  than 
soluble  starch  to  throw  it  out  of  solution,  it  is  much  more  difficult  to 
completely  free  it  from  ammonia  salts  and  fixed  ash.  These  were 
finally  removed  by  dialysis,  and  the  recovered  '  dextrin'  was  precipi- 
tated several  times  with  alcohol  until  its  optical  properties  were 
constant. 

The  optical  and  reducing  values  for  the  recovered  product  are  here 

„.  „„  ,  ^oogfe 


STARCH  BERIYATIYES  THROUQH  THEIR  NITRATES.  311 

given   for  two   distinct  preparations,  the  values  for  the   original 
dextrin  being  also  given  for  comparison. 


[a]^ 

R. 

Original  dextrin 

196-0° 

5-5 

*  Dextrin '  recovered  from  nitrates. 

Prep.  (1) 

1910 

0 

Prep.  (2) 

188-4 

0-4 

Although  at  first  sight  it  may  appear  that  a  non-reducing  dextrin 
of  high  optical  activity  has  been  recovered,  such  is  really  not  the 
case.  If  the  reducing  portion  of  the  original  dextrin  with  an  B  of 
5*5  had  been  merely  separated  in  the  process  of  nitrification  and 
fractionation,  we  should  expect  the  specific  rotatory  power  of  the 
recovered  '  dextrin '  to  be  correspondingly  increased,  instead  of  being 
materially  decreased,  as  it  in  fact  is. 

The  distinct  acid  character  of  the  recovered  '  dextrin '  is  a  proof 
that  the  original  dextrin  had  been  oxidised  by  the  treatment  with 
nitric  acid,  and  that  we  have  been  really  dealing  with  the  nitrate  of 
a  polysaccharide  acid,  and  not  with  that  of  the  original  dextrin,  which 
is  without  acid  characters. 

This  is  a  matter  which  will  be  found  more  fully  dealt  with  in  the 
next  paper ;  it  is  sufficient  for  our  present  purpose  to  know  that  the 
nitration  and  recovery  method  is  not  applicable  to  the  purification  of 
the  stable  dextrin. 

NUrcUion  and  AiUmpted  Recovery  of  AmylodextHn, 

The  name  amylodextrin  was  applied  by  W.  Nageli  in  1874  to  a 
substance  which  he  obtained  by  the  long-continued  action  of  dilute 
mineral  acids  on  ungelatinised  starch  in  the  cold.  Unfortunately,  of 
late  years,  a  considerable  amount  of  confusion  has  been  introduced 
into  the  nomenclature  of  starch  products  by  an  application  of  the 
same  name  by  C.  J.  Lintner  and  others  to  another  substance  which  is 
identical  with  the  'soluble  starch '  of  O'Sullivan,  Musculus,  and 
ourselves. 

In  1889,  one  of  us  and  Morris  (Trans.,  1889, 65,  449)  described  the 
results  of  an  investigation  of  Nageli's  amylodextrin,  and  it  was 
shown  to  be  a  well-defined  substance  belonging  to  the  class  of  malto- 
dextrins  or  amyloins.  It  separates  from  its  solutions  in  the  form  of 
sphflsro-erystals,  and  has  optical  and  reducing  properties  correspond- 
ing to  [a]y8-8«  206-1  and  icsse  9*08  (=  [ajo  192-0°,  R  14-9) 

It  was  regarded  as  constituted  of  six  amylin  groups  combined 
with  one  amylon  gronp,  and  consequently  having  the  empirical  formula 

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312   BROWN  AND  MILLAR:  ATTEMPTS  TO  PREPARE  PURE 

In  the  light  of  our  recent  work  on  maltodextrin,  described  in 
the  previous  paper,  the  constitution  of  amylodeztrin  will  doubtless 
be  expressed  in  the  abbreviated  form  by 

O^^l  2^20^9 

A  part  of  the  actual  preparation  of  amylodeztrin  described  in  the 
1889  paper  was  submitted  to  nitration  under  the  usual  conditions. 

4*800  grams  yielded  7'78  grams  of  nitrate  (162  percent.),  which  came 
down  on  successive  treatment  with  sulphuric  acid  and  water  as  a  white, 
amorphous  powder,  very  soluble  in  ether,  acetone,  and  ethy lie  acetate, 
but  insoluble  in  chloroform  and  light  petroleum. 

Three  fractional  precipitations  were  made  with  chloroform  from  its 
solution  in  etbylic  acetate.  These  gave  the  following  amounts  of 
nitrogen. 

Fraction  (1)     10-81  per  cent.  N. 

(2)  10-66     „      „ 

(3)  11-50    „      „ 

Supposing  it  to  be  a  true  nitrated  derivative  of  the  unaltered 
amylodeztrin,  this  corresponds  very  nearly  with  the  28-nitrate,  which 
requires  11*0  per  cent,  of  nitrogen. 

The  nitrate  was  treated  in  the  usual  manner  with  ammonium 
sulphide,  and  the  recovered  amylodeztrin  precipitated  with  alcohol ; 
it  was  obtained  perfectly  free  from  ash,  and  in  the  form  of  minute 
sphserocrystals.  The  optical  and  reducing  properties  of  the  original 
and  recovered  products  are  here  given. 

[o]d  R. 

Original  amylodeztrin  192*0         14*9 

Amylodeztrin  recovered  from  nitrate         181*0         8*1 

It  is  evident  that  the  substance  has  been  much  altered  during 
the  process,  and  that  the  method  of  recovery  is  not  applicable  to 
amylodeztrin. 

Ntiration  and  Attempted  Recovery  qf  McUtodeoetrin, 

4*686  grams  of  carefully  dried  maltodeztrin,  on  nitration,  yielded 
7-094  grams  of  the  nitrate  (151  per  cent.).  This  is  very  soluble  in 
85  per  cent,  alcohol,  and  also  in  ether  and  ethylic  acetate.    From  its 


STARCH  DERIVATIVES  THROUGH  THEIR  NITRATES.         313 

ethereal  solution,  it  is  thrown  down  by  light  petroleum  in  the  form  of 
oily  dropS;  but  is  only  partially  separable  by  chloroform.  Chloroform 
does  not  precipitate  it  from  its  solution  in  ethylic  acetate,  and  light 
petroleum  only  partially. 

The  nitrate  was  fractionated  by  partial  precipitation  with  light 
petroleum,  evapyration  of  the  mother  liquors,  re-solution  in  ethylic 
acetate,  and  further  precipitation  with  light  petroleum.  Two 
fractions  prepared  in  this  manner  gave  the  following  amounts  of 
nitrogen  by  Lunge's  method. 

Fraction  (1)       7*80  per  cent.  N. 
(2)    10-34     „       „ 

The  mixed  nitrates,  on  treatment  with  ammonium  sulphide,  gave  a 
substance  which  had  the  appearance  of  maltodeztrin,  but  was  of  an 
acid  nature  and  had  been  reduced  in  specific  rotatory  and  reducing 
powers  to 

Wd  185-1 
R    26-3. 

Alterations  have,  therefore,  occurred  during  nitration,  and  the 
recovered  product  is  not  identical  with  the  original. 

Ni^^aiion  cmd  Attempted  Recovery  of  Maltose. 

The  nitrate  was  readily  obtained  as  a  white,  amorphous  solid,  which, 
after  well  washing  with  water,  was  re-dissolved  several  times  in 
ethylic  acetate  and  precipitated  by  chloroform,  which  brings  it  down 
as  a  syrup.  This  was  separated,  and  after  partial  drying,  the  product 
was  powdered  and  completely  dried  until  the  weight  was  constant. 
Lunge's  method  showed  13*9  per  cent,  of  nitrogen  in  the  purified 
substance.  The  hezanitrate,  O^JELiQ^ii^^sief  requires  13*72  per  cent, 
nitrogen. 

This  nitrate  did  not  yield  pure  maltose  on  treatment  with  ammonium 
sulphide,  the  specific  rotatory  power  of  the  solution  being  very  much 
higher  than  it  should  have  been  if  the  cupric  reduction  were  taken  as 
a  measure  of  the  maltose  present. 

Nevertheless,  the  presence  of  maltose  in  the  mixture  was  ascertained 
by  the  formation  of  maltosazone. 

General  Remarke. 

It  will  be  observed  that  the  regeneration  of  the  original  starch 
derivative  in  anything  like  a  pure  state  from  its  nitrate  was  only 
found  possible  in  one  case,  that  of  soluble  starch.     In  all  those 


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314     ATTEMPTS  TO  PREPABE  PURE  STARCH  DERIVATIVES,  ETC. 

instances  in  which  the  starch  derivative  under  experiment  was  cupric- 
reducing — that  is,  contained  the  open  carbonyl  group — ^the  properties 
of  the  regenerated  product  indicated  that  more  or  less  oxidation  had 
taken  place,  and  that  the  ethereal  nitrate  was  an  indeterminate 
mixture  of  a  nitrate  of  the  original  carbohydrate  and  of  a  nitrated 
carboxylic  acid  or  acids.  This  line  of  work,  commenced  in  the  early 
part  of  1897,  was  consequently  abandoned,  since  it  did  not  promise 
to  lead  to  the  object  we  had  in  view,  the  separation  and  identifica- 
tion of  the  intermediate  products  of  starch-hydrolysis. 

Since  that  time  an  important  paper  on  the  nitration  of  carbo- 
hydrates has  been  published  by  Will  and  Lenze  {Ber.,  1898,  30,  68) 
in  which  they  give  an  account  of  their  examination  of  most  of  the 
principal  carbohydrates  from  this  point  of  view.  They  found  that, 
with  the  exception  of  the  lactoses,  most  of  them  are  readily  converted 
into  nitrates,  and  in  many  cases  these  were  obtained  crystalline,  and 
with  such  well  characterised  properties,  that  the  process  may  be  used 
for  identification  of  uncertain  carbohydrates  and  their  recognition  in 
mixtures.  An  attempt  to  regenerate  the  original  substance  appears 
to  have  been  made  only  in  one  instance,  that  of  Fischer's  a-methyl- 
glucoside,  whose  tetranitrate  yielded  the  parent  substance  when  an 
alcohob'c  solution  was  treated  with  ammonia  and  hydrogen  sulphide. 

Of  the  substances  described  in  our  present  paper,  the  authors 
examined  only  starch  and  maltose.  The  former  gave  an  amorphous 
hexanitrate,  whilst  from  the  nitrated  products  of  the  latter  a  crystalline 
substance  was  obtained  whose  nitrogen  content  corresponded  to 
maltose  octonitrate. 

Had  we  been  successful  in  obtaining  definite  nitrates  of  the  inter* 
mediate  starch  derivatives,  it  was  part  of  our  plan  to  determine  their 
molecular  weight  by  the  freezing  point  method.  We  have,  in  fact, 
made  these  determinations,  but  from  what  has  been  said  it  is  evident 
that  they  are  without  value,  and  we  consequently  have  not  given 
them  here. 

We  may,  however,  refer  to  the  examination  of  the  derivative  of 
soluble  starch  from  this  point  of  view,  since  everything  pointed  to  the 
derivative  in  this  case  being  a  perfectly  definite  trinitrate. 

The  determination  was  made  in  acetic  acid,  whose  constant  of 
molecular  depression  had  been  determined  by  means  of  naphthalene. 

The  result  gave  a  value  for  Ma>987.  The  molecular  weight  of 
2[Ci2HiA(NO«)3]  is  918. 

From  all  we  know  about  the  constitution  of  soluble  starch  from 
other  sources,  it  is  quite  certain  that  the  value  of  n  in  the  formula 
n(Oj2H2oOio)  must  be  far  greater  than  2,  so  we  must  conclude  that 
the  freezing  point  method  applied  to  such  derivatives  of  the  colloidal 


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THE  STABLE  DEXTRIN  OF  STABCH  TBANSFOBMATIONS,  ETC.  315 

carbohydrates  as  we  are  considering  is  quite  inapplicable  to  the 
determination  of  molecular  weight;  and  the  same  probably  applies 
to  the  colloidal  carbohydrates  themselves. 

The  Davy-Fabaday  Reseakch  Laboratoky, 
Royal  Institution. 


XXXII. — The  Stable  Dextrin  of  Starch  Transformations, 
and  its  Relation  to  the  Maltodextrins  and  Soluble 
Starch. 

By  Ho&ACB  T.  Bbown,  LL.D.,  F.R.S.,  and  J.  H.  Millae. 
Contents. 

PAOB 

I.  Intiodnction 315 

II.  Separation    and    Purification    of    the    Stable 

Dextrin 317 

HI.  Is  the  Stable  Dextrin  a  Reducing  Substance  9  .        322 
lY .  Oxidation  of  the  Stable  Dextrin  and  Formation 

of  Dextrinic  Acid 325 

y.  Nitration  and  Subsequent  Recovery  of  Dextrinic 

Acid 326 

YI.  Analysis  of  Calcium  Salt  of  Dextrinic  Acid     .         328 
yn.  Hydrolysis  of  Dextrinic  Acid  with  Oxalic  Acid 

and  Diastase 328 

ym.  Hydrolysis  of  the  Stable  Dextrin  with  Oxalic 

Acid  and  Diastase 330 

IX.  Generalisations  and  Conclusions  .         .        331 

I.  Introduction. 

It  was  shown  by  one  of  us  and  Heron  in  1879  (Trans.,  1879;  36,  596, 
that  when  gelatinised  starch,  or  soluble  starch,  is  hydrolysed  with  a 
little  cold-water  malt-extract  at  temperatures  below  60°,  the  reaction 
proceeds  with  great  rapidity  until  the  mixed  products  of  transforma- 
tion show  a  cupric  reduction  corresponding  to  about  80  per  cent,  of 
maltose,  and  a  specific  rotation  very  close  on  [a}i>  150°.*  With  an 
active  diastase,  this  point  may  be  reached  in  less  than  5  minutes,  and 
further  change  is  comparatively  very  slow  indeed. 

*  At  oidiiMty  tempentaies,  the  tpecific  rotatorylpower  may  be  temporarily  lower 
than  thia  owing  to  the  maltoee  being  liberated  in  the  birotatory  state.  (See  Trans. , 
1895,  67,  809.) 


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316      BROWN  AND  MILLAR:  THE  STABLE  DEXTRIN   OF  STARCH 

This  fact  has  been  referred  to  many  times  in  our  papers,  and  was 
illustrated  in  the  1879  paper  by  a  series  of  time  carves,  and  again  in 
the  same  manner  in  a  paper  on  amylodextrin  published  in  1889 
(Trans.,  65,  457). 

These  values  of  [ajo  150  and  B  80  mark,  in  fact,  a  definite  resting 
point  in  the  reaction,  beyond  which  it  is  difficult  to  push  it,  unless  a 
considerable  amount  of  time  is  allowed. 

That  the  cessation  of  action  is  due  neither  to  the  weakening  of  the 
enzyme  nor  to  the  action  being  a  reversible  one,*  may  be  readily  shown 
in  a  variety  of  ways.  For  instance,  (1)  the  addition  of  more  enzyme  has 
no  appreciable  effect  in  hastening  the  very  slow  subsequent  change 
after  the  resting  point  has  been  reached  ;  (2)  if  more  gelatinised 
starch  or  soluble  starch  is  added  to  the  solution,  it  is  speedily  brought 
to  the  same  condition  of  optical  activity  and  reducing  power;  (3) 
when  a  complete  or  partial  separation  of  the  maltose  is  effected  by 
suitable  means,  as  by  fermentation  or  fractionation  with  alcohol,  the 
residual  dextrin  shows  the  same  resistance  to  further  hydrolysis  with 
diastase  as^o  the  mixed  products  which  have  attained  the  resting 
stage. 

In  the  1879  paper  {loc.  cit),  it  was  also  shown  that,  if  we  assume 
the  whole  of  the  reducing  substance  to  be  maltose,  the  resting  point 
of  the  reaction  corresponding  to  [aJD  150°  and  It  80  agrees  very 
closely  with  the  view  that  the  starch  has  been  hydrolysed  according 
to  the  following  empirical  equation, 

lOCijHjoOio   +   SKfi  =   8C12H22O11   +   2C12H20O10 
Starch.  Maltose.  Dextrin. 

which  requires  80*8  per  cent,  of  maltose  in  the  products  of  trans- 
formation. 

This  was  the  so-called  '  No.  8  equation,'  which  at  that  time  was 
supposed  to  represent  only  one  of  several  other  halting  points  in  the 
hydrolysis.  We  are  now  of  opinion  that  this  well-marked  resting 
stage,  corresponding  to  [ajo  150,  R  80,  is  the  only  one  which  admits, 
with  certainty,  of  being  expressed  by  any  definite  equation. 

From  the  solution  of  the  starch  products  which  have  been  allowed 
to  reach  the  above-mentioned  point,  crystallisable  maltose  can  readily 
be  prepared  by  extraction  with  alcohol  of  80  per  cent.,  or  the  maltose 
can  be  fermented  out  by  yeast.  By  either  of  these  methods  of  treat- 
ment, by  far  the  greater  part  of  the  reducing  substance  may  be 
removed,  and  in  this  respect  these  complete  starch  transformations 
stand  in  strong  contrast  with  those  in  which  the  resting  stage  has  not 

*  By  this  we  do  not  mean  to  imply  a  denial  that  the  action  may  not  be  to  some 
extent  a  reveraible  one,  but  only  that  this  particalar  effect  cannot  be  due  to 
reyeraion. 


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TAAKSFORMATIONS,  AND  RELATION  TO  MALTODEXTRINS,  ETC.       317 

been  fully  attained,  since,  in  all  incomplete  conversionB,  the  reducing 
constituent  is  not  present  wholly  as  crystallisable,  fermentable  maltose, 
but,  in  part,  at  any  rate,  as  maltodeztrins.  Complete  and  incomplete 
conversions  also  differ  from  one  another  in  their  behaviour  towards 
phenylhydrazine.  If  the  transformation  products  have  reached  the 
resting  stage  corresponding  to  [aj^  150,  R  80,  the  yield  and  purity 
of  maltosazone  is  much  greater  than  is  obtained  from  a  proportional 
amount  of  an  incomplete  transformation  which  might  be  assumed, 
from  its  reducing  power  only,  to  contain  an  equal  amount  of  maltose. 
Indeed,  all  the  available  facts  bear  out  the  supposition  that  in  a 
complete  conversion  which  has  attained  the  resting  stage,  the  greater 
part,  if  not  the  whole,  of  the  reducing  power  is  due  to  free,  crystallis- 
able,  and  readily  fermentable  maltose. 

Such  a  solution,  besides  maltose,  contains  an  achroodeztrin, 
which  is  precipitable  by  alcohol  of  80 — 85  per  cent.  This  dextrin, 
amounting  to  about  20  per  cent,  of  the  starch  originally  taken,  is 
attacked  only  with  difficulty  by  diastase,  and  differs  in  this  respect 
from  all  the  intermediate  dextrinous  products,  amongst  which  is 
the  maltodeztrin  which  has  been  the  subject  of  a  previous  paper. 

We  have  submitted  this  stable  dextrin  to  a  careful  re-examination 
during  the  past  two  years,  and  the  present  paper  deals  with  our  most 
recent  conclusions  with  regard  to  its  nature,  properties,  and  con- 
stitution. 

The  difficulties  of  obtaining  the  stable  dextrin  in  a  state  of 
purity  are  considerable,  and  even  greater  than  they  are  in  the  case 
of  maltodextrin.  This  arises  from  the  fact  that  the  process  of 
treatment  with  alcohol  necessarily  tends  to  concentrate  in  the  final 
insoluble  product  all  impurities  pre-existent  in  the  starch  and  the 
transforming  agent,  which  happen  to  be  insoluble  in  the  lowest 
strength  of  alcohol  used  in  the  separation. 

If  fermentation  has  also  been  employed,  there  is  the  additional 
risk  of  introducing  small  amounts  of  nitrogenous  impurities,  and 
also  some  of  the  non-volatile  products  of  fermentation,  although  the 
latter  are,  for  the  most  part,  removable  by  the  subsequent  treatment 
with  alcohol. 

The  ^actual  amount  of  such  impurities,  which  may  amount  to 
2 — 3  per  cent.,  can  be  determined  with  a  close  approximation  to 
accuracy  by  submitting  the  separated  dextrin  to  the  standard 
methods  of  acid  hydrolysis  described  in  the'previous  paper  (p.  305). 

II.  Separation  oflnd  Parificatum  of  the  StaUe  Dextrin. 

In  these  experiments,  we  always  commenced  with  from  2000  to 
3000  grams  of  well-wasl)ed  potato  starch,  which  was  brought  into 

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318      BROWN   AND  MILLAR:  THE  STABLE  DEXTRIN  OF  STARCH 

solution  with  from  16  to  20  litres  of  water  by  successive  gelatin!- 
sations  and  liquefactions,  in  the  manner  described  in  our  previous 
paper  on  maltodextrin  (this  vol.,  p.  288).  We  thus  obtained  the 
starch  solids,  for  the  final  conversion,  at  a  concentration  of  from 
12  to  15  per  cent.  The  preliminary  conversions  at  65 — 70®  were 
allowed  to  go  sufficiently  far  to  prevent  any  of  the  higher  starch 
transformation  products  coming  out  of  solution  when  the  tempera- 
ture was  reduced  to  15 — 20^  The  completion  of  the  conversion 
down  to  the  ^  resting  point/  corresponding  to  [a]D  150®,  R  80,  was 
then  carried  out  at  the  ordinary  temperature,  with  the  aid  of  cold- 
water  malt-extract,  made  from  a  very  diastasic  air-dried  malt.  This 
conversion  sometimes  lasted  for  two  days  *  or  more,  the  object  being 
to  select  the  best  conditions  for  producing  a  low  conversion,  with  the 
employment  of  the  minimum  amount  of  malt-extract.  The  importance 
of  this  condition  is  rendered  evident  by  what  we  have  already  said 
about  the  concentration  of  impurities  on  the  dextrin  during  the  sub- 
sequent processes  of  its  extraction. 

The  actual  amount  of  '  normal '  t  malt  extract  required  was  from 
3  to  6  c.c.  of  the  extract  per  100  c.c.  of  a  solution  containing  from 
9  to  15  grams  of  starch  products.  This  is  equal  to  from  0*3  to  0*4 
c.c.  of  extract  per  gram  of  starch  converted,  and  represents  about  the 
minimum  amount  which  can  be  used  for  these  complete  conversions. 
The  actual  amount  of  solids  introduced  with  the  malt -extract  repre- 
sents about  3*5  per  cent,  of  the  starch  used,  but  by  far  the  greater 
part  of  these  solids  are  separable  by  alcohol  of  from  75 — 90  per  cent., 
and  are  removed  in  the  processes  of  purification  to  which  the  dextrin 
is  submitted. 

After  the  conversion  had  been  run  down  to  the  desired  point,  the 
solution,  filtered  from  a  certain  amount  of  '  starch-cellulose,'  which 
always  separates  during  starch  transformations  made  in  the  cold, 
was  evaporated  to  a  thick  syrup.  The  process  of  separation  was 
then  commenced;  this  consisted  of  fractionation  with  alcohol  of 
various  degrees  of  strength  with  occasional  recourse  to  fermenta- 
tion. The  treatment  with  alcohol  was  varied  in  every  conceivable 
manner. 

It  would  be  tedious  and  unprofitable  to  give  anything  but  a  mere 
sketch  of  the  process,  since,  at  this  stage,  it  did  not  differ  materially 
from  similar  methods  we  have  frequently  described  before,  except  as 
regards  the  number  of  operations  and  the  length  of  time  required, 
often  amounting  to  severed  months  for  each  experiment. 

•  The  solution  was  occasionally  sterilised,  with  the  further  addition  of  malt 
extract. 

t  '  Normal  *  malt  extract  is  obtained  by  digesting  finely  divided  malt  (air  dried) 
with  2*5  times  its  weight  of  cold  water,  and  filtering  after  6  hours. 


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TRAK8FORMATI017S,  AND  RELATION  TO  MALTODEXTBINS,  ETC.      319 

We  will  briefly  describe  the  coarse  of  one  experiment,  which  is 
typical  of  all. 

A  conversion  of  2400  grams  of  starch  which  had  been  run  down 
to  the  '  resting  stage '  and  evaporated  to  a  syrup  was  treated  in  the 
first  place  with  7  litres  of  hot  alcohol  of  90  per  cent.,*  the  strength 
of  the  alcohol  in  the  mixture  being  75 — 80  per  cent. 

About  200  grams  of  dextrin  separated.  The  alcoholic  solution, 
poured  off  when  cold,  was  distilled,  and  the  syrupy  residue  poured 
into  6  litres  of  boiling  spirit  of  96 '5  per  cent.,  and  digested  for  some 
time.  The  second  dextrinous  residue  thus  obtained  was  further 
digested  with  86  per  cent,  spirit,  the  insoluble  portion  being  added 
to  the  original  residue  of  200  grams.  The  alcoholic  solutions  on 
distillation  yielded  a  syrup  from  which  maltose  readily  crystallised. 

The  combined  dextrinous  portions,  amounting  to  660  grams,  now 
contained  only  42  per  cent,  of  maltose,  as  against  80  per  cent,  in  the 
original  starch  transformation  products.  This  crude  dextrin  was 
dissolved  in  6  litres  of  water,  and  the  solution,  having  a  sp.  gr.  of 
1042*6,  was  set  to  ferment  with  16  grams  of  washed  and  pressed  yeast. 
During  the  progress  of  the  fermentation,  which  lasted  for  10  days, 
an  examination  of  the  solution  was  made  from  time  to  time,  and  it 
was  shown  that,  whilst  the  specific  rotatory  power  of  the  unfermented 
matter  steadily  increased,  the  optical  properties  of  the  portions 
fermented  at  any  stage  corresponded  with  those  of  maltose. 

The  fermented  solution,  which  now  gave  only  a  trace  of  insoluble 
osazone  on  treatment  with  phenylhydrazine,  was  evaporated  to  remove 
alcohol.    The  specific  rotatory  power  of  the  residue  was  [a ]j,  182*5°. 

In  order  to  remove  any  trace  of  maltodextrin,  the  solution,  made  up 
to  sp.  gr.  1043,  was  now  once  more  treated  for  2  hours  at  50°  with 
40  C.C.  of  a  very  active  malt  extract.  It  was  then  once  more  heated 
to  the  boiling  point,  cooled,  and  again  set  to  ferment  with  11  grams 
of  washed  yeast  for  5  days,  during  which  time  14*04  grams  of  ferment- 
able substance  disappeared,  which  represents  about  3*0  per  cent,  of 
the  540  grams  of  the  crude  dextrin.  The  optical  properties  of  this 
fermentable  substance  were  again  found,  by  the  usual  process  of 
fractional  fermentation,  to  correspond  with  those  of  maltose. 

Two  precipitations  were  then  made  with  85  per  cent,  alcohol,  and 
the  dextrin  obtained  was  submitted  to  nine  successive  extractions 
with  boiling  alcohol,  each  extraction  lasting  for  a  day  or  more,  the 
mixture  being  frequently  agitated.  The  first  six  of  these  extractions 
were  made  with  alcohol  of  86  per  cent.,  and  the  other  two  with 
alcohol  of  80  per  cent.  The  weights  and  specific  rotatory  powers  of 
the  matter  extracted,  and  the  specific  rotatory  power  of  the  residual 
dextrin  after  each  extraction,  were  determined. 

*  Throughout  the  paper,  the  percentages  of  alcohol  are  expressed  by  volume. 


320   BBOWN  AND  MILLAR  :  THE  STABLE  DEXTRIN  OF  STARCH 

The  results  of  the  nine  successive  treatments  at  this  stage  are  here 
tabulated. 

The  amount  of  crude  dextrin  at  the  commencement  was  492  grams. 

Table  I. 


No.  of  fraction. 

Extracted  with  alcohol. 

Residual  dextrin. 

Weight. 

[«]^. 

[«P. 

hit 

00           ^6 

liili 

Grams. 

10-66 

8-14 

9-89 

9-63 

2-51 

7-07 

22  12 

22-34 

17  11 

115-7'* 

127-8  * 

145-7 

166-3 

167  1 

168-2 

174-6 

166-9 

177-7 

ISfi-S** 

186-9 

186-8 

186-7 

188-2 

187-5 

186-8 

*  These  extractions  contained  the  non-Tolatile  prodncts  of  fermentation  and  the 
sugars  of  the  malt-extract. 

It  was  evident  that  the  method  of  separation  adopted  up  to  this 
point  had  practically  reached  the  experimental  limits,  so  a  different 
plan  of  treatment  was  now  adopted. 

The  dextrinous  residue,  after  the  ninth  treatment,  amounting  to 
383  grams  of  substance  with  an  [ajo  of  186*8°,  was  dissolved  in 
1000  c.c.  of  water,  and  cdd  alcohol  of  85*5  per  cent,  was  gradually 
added,  until  precipitation  just  commenced.  The  precipitate  containing 
albuminous  matter  was  rejected.  Alcohol  of  85-5  percent,  was  again 
added  with  constant  agitation,  until  about  one-third  of  the  dextrin 
was  thrown  down.  This  is  fraction  A,  and  it  was  separately  treated 
by  dissolving  it  in  its  own  weight  of  water,  and  precipitating  in  two 
fractions,  A^  and  Ag,  by  the  further  addition  of  85  per  cent,  spirit. 

These  fractions  had  the  following  properties. 

Ai         [a]o  193-1         R  6-6 
Ag         [a],>  193-0  — 

The  clear  solution  from  A  was  again  precipitated  in  the  cold  with 
alcohol.  On  heating,  the  precipitate  redissolved,  but  was  again  thrown 
out  on  cooling — this  is  fraction  B.  After  the  removal  of  the  precipi- 
tate, the  liquid  was  increased  in  alcoholic  strength,  in  the  first  place 
to  85  per  cent.,  and  in  the  second  to  95  per  cent.,  the  fractions  thus 
obtained  being  C  and  D.  The  final  mother  liquor  from  D  was  mixed 
with  that  from  A^,  and  the  55  grams  constituting  fraction  E  were 

Digitized  by  VjOOQIC 


TRANSFORMATIONS,  AND  RELATION  TO  MALTODEXTRINS,  ETC.      821 

freed  from  alcohol  and  separated  into  two  parts,  E^  and  E^,  with 
95  per  cent,  alcohol.  These  latter  fractions  had  the  following  specific 
rotatory  power. 

Fraction  B     [a]i>  192-1°  Fraction  E     [a]i>  184-9° 

C     [a]D  190-8  Ej    [a]i,  186-6 

D     [aJD  189-0  Ej    [a],>  179-7 

It  is  clear  from  the  above  that  the  dextrin  which  could  not  be 
further  separated  by  the  nine  treatments  with  alcohol  described  in 
Table  I  has  given  way  to  the  modifications  in  the  alcohol  treatment 
just  described,  products  being  obtained  amongst  the  least  soluble 
portions  with  specific  rotatory  powers  as  high  as  [aj^  193-0° 

The  above  fractions  A^,  Aj,  B,  d  and  D,  with  rotatory  powers  of 
from  [a]]>  189*0  to  [a]i>  193*1  were  now  united  and  subjected  to  still 
further  treatment. 

After  being  evaporated  to  a  thick  syrup,  they  were  gradually  treated 
with  2  litres  of  hot  86  per  cent,  alcohol ;  after  digestion  for  6  hours, 
the  alcoholic  solution,  when  cold,  was  poured  off,  and  the  properties 
of  the  residue,  and  those  of  the  small  quantity  of  extracted  matter, 
were  examined.     These  were  as  follows. 

Dextrinous  residue [ajn  192*7° 

Portion  soluble  in  alcohol...     [a]^  183*6 

This  process  was  repeated  twice  more,  and  the  dextrin,  which  had  now 
been  reduced  to  about  200  grams,  was  obtained  with  a  specific  rotatory 
power  of  [a]D  192-0°. 

We  now  once  more  resorted  to  fractionation.  The  200  grams  of 
dextrin  were  dissolved  in  500  c.c.  of  water,  and  500  c.c.  of  alcohol  added  in 
the  cold ;  the  addition  of  100  c.c.  more  of  96  per  cent,  alcohol  brought 
down  fraction  F ;  this,  when  redissolved  in  200  c.c.  of  water  and  again 
treated  with  250  c.c.  of  96  per  cent,  alcohol,  gave  a  precipitate  which, 
by  further  similar  treatment,  was  resolved  into  fractions  F^,  F3,  and 
F^,  having  the  following  optical  and  reducing  properties. 


[«K 

B. 

F, 

194-7° 

5-9 

Fa 

196-6 

6-9 

F4 

195-4 

— 

It  must  be  remembered  that,  in  the  protracted  and  laborious  treatment 
of  separation,  which  ishere  only  described  inavery  condensed  form,  every 
conceivable  variation  of  treatment  with  alcohol  was  adopted,  whilst 
the  process  was  further  supplemented  by  occasional  treatment  with 
diastase  to  break  down  any  maltodextrin  which  might  remain  adherent 
to  the  product,  and  also  by  employing  fermentation  to  assist  in  the 
elimination  of  the  maltose.  ^  ^ 

Digitized  by  VjOOQIC 


322     BROWN  AND  MitLAR :  THE  STAbLfi  D^lTRlK  Oi  STAttCtt 

In  all  similar  experiments,  no  matter  how  long  the  alcoholic  frac- 
tionation may  have  heen  continued,  we  have  always  obtained  the  same 
final  result.  A  point  is  ultimately  reached,  sometimes  comparatively 
speedily,  when  no  further  change  takes  place  in  the  properties  of  the 
separated  dextrin.  This  is  marked  by  the  product  assuming  optical 
and  reducing  properties  corresponding  to 

[a]Dl95— 196« 
R     5-5— 6-9 

Such  a  product  is,  however,  never  quite  free  from  ash,  which  amounts 
to  0*3  to  0*5  per  cent,  of  the  dry  weight,  and  it  also  contains  a  trace 
of  nitrogen  corresponding  to  about  0*2  per  cent,  of  albuminoids. 
Hence  the  above  values  of  [  a  ]d  and  R  are  slightly  lower  than  those 
corresponding  to  the  pure  carbohydrate ;  the  error  introduced  from 
this  cause  does  not,  however,  exceed  more  than  2°  in  the  specific 
rotatory  power,  and  will  have  no  appreciable  effect  on  the  value  of  R. 

Prepared  in  this  manner,  this  dextrin  is  obtained  as  a  white, 
amorphous,  gummy  substance,  soluble  in  water  to  any  extent,  and 
completely  separable  from  its  aqueous  solutions  in  the  cold  by  alcohol 
of  80  per  cent.,  which  brings  it  down  as  a  waxy  solid  with  a  silky 
lustre. 

Dried  at  100^  in  a  vacuum  over  phosphoric  anhydride,  it  has  a 
divisor  of  3*995  for  a  solution  density  of  1054*49. 

One  of  the  chief  characteristics  of  this  dextrin,  prepared  from  starch 
conversions  which  have  attained  the  *  resting  stage,'  is  the  relative 
difficulty  with  which  it  is  attacked  by  diastase,  as  compared  with  the 
small  power  of  resistance  exhibited  by  the  intermediate  products.